Small Unit Tactics

Marc: "As a matter of fact, I do. I also have stuff on military-style small unit tactics."

Generally, you want things like interlocking fields of fire (which allow more than one operative to engage a single target from different directions), overwatch (use the rules for held action in SRII, i.e. sammi comes around the corner into the waiting caress of a hail of 7.62mm FMJ), suppressive fire (see the rules for suppressive fire in Fields of Fire), and other nasty stuff. Actually, you have quite a bit of it already if you are using duckback sighting and cover. Those are extremely important.

Also don't deprive your goons of the abilities of communications and sensory detection. For example, instead of having two goons blast around a corner and hose, have one goon use 1 simple action to look around the corner and make a perception test (to spot all possible targets if there are more than one and to determine the placement and threat assessment of those targets. That goon then uses his other simple action to duck back into full cover (totally out of the players' line of sight) and use his free action to convey the information obtained in either word or gesture (i.e. a one word/gesture way of pointing out the most significant threat). Then goon 2 (whose action is held till this point) ducks out around the corner and takes a single shot/burst at the target designated by the first. Goon 2 then ducks back into full cover, or stays out and covers the hall, depending on the result of his shot.

Also, you might want to allow the holding of simple actions, i.e. you can jump out, fire a burst, then hold your other simple action in case someone else comes into the hall. If something happens and you decide to use that held action, it can only be something that could be accomplished in a simple action. It works wonders.

As far as sensory detection goes, thermographic vision is the shit. It doesn't take long for someone's heat signature to bleed through a wall or door, probably only about two combat rounds. So if a player stays put for any length of time, assume the guards know where he or she is, and they can act accordingly (like hose through the door or wall). Better still, this is not blind fire since you can see the target, although you may want to apply a small (+2 ?) modifier for the fuzziness of the bleed-through signature.

Further suggestions:

1. Don't go into combat alone. Nobody likes to be outnumbered, especially the bad guys. Unless your operatives are extremely competent badasses, they will come in twos and threes. SWAT teams like to have something like, one guy break down the door and get the hell out of the way, while the three guys behind him quickly enter and take up overwatch positions, engaging and neutralising hostiles as necessary. In two or three man teams, you have all the benefits of combined firepower, multi-directional line-of-sight, and bounding overwatch capability (I'll get to this later), without having to take headcounts to see if anybody is missing. If you can look around and see two other guys, you know you're in the clear.
2. Communicate. Don't underestimate the power of the forward observer. The information age has shown us that knowledge is power. Use it. By sending in a drone, the operatives may know the position of any hostiles, hostages, or innocent civvies caught in the fray. By having that sniper-spotter also carry a laser microphone, he can not only spot a target but he can listen to what that target is saying. If the party is dumb enough to make plans on site, use that against them and have people waiting for them in ambush. If one operative knows some crucial bit of intelligence, he'll pass it along to his buddies. So assume that if one of them can see you, they all know where you are (roughly at the very least).
3. Plan ahead. If a situation has developed, SWAT/Military deckers will have downloaded stuff like building plans, etc. so they may know the most likely places the party may be. They will also know the layout of the building, And may be able to exploit service access, crawl-spaces, maintenance tunnels, etc. They will also know which ways NOT to come in. Stepping down to the "security goon" level, it is entirely possible that the security personnel may have "secret doors" leading between critical areas to speed up deployment and add an element of surprise. It is also possible that these security tunnels may not appear on any building plan the players will ever get hold of. Talk about goons coming outta the walls...
4. Do your homework. Once on site, some hotshot recon weenie will get a picture/voice print/DNA sample of the perpetrator(s) (again, the little drones are wonderful for this). From this, those same SWAT/military deckers may be able to determine the ID of the perp(s). They will use this to the best of their advantage; for example, say the SWAT team finds out that Bad-Ass George, the notorious samurai, has holed up inside a building with his team of runners. Say poor George has a criminal record. Uh, oh. Say this record tells the coppers that ol'Bad-Ass has a cybernetic inhaled filtration system and Wired-3. Wow. So maybe instead of tossing in just those Neurostun canisters, they'll throw in some EMP grenades too, just special for George (BTW, an EMP [E-lectro M-agnetic P-ulse] grenade is a CP 2020 thing, but perfectly plausible in today's day and age, and appropriate for Shadowrun. It's pretty much death to cyberware). And even if that doesn't work perfectly, they know who their primary target is, right? Also keep in mind that the identities may be determined before the cops even arrive (like from the footage of various security cameras, etc.) Forewarned is forearmed. This is not even taking into account the possibility of obtaining a material link (drop of blood, piece of hair or skin), which is a whole different ball of wax.
5. Cover your ass. Don't have your operative step out into the open, especially when he or she doesn't know what's out there. Partial cover, movement modifiers, etc. can all play significant roles. Especially now that the revised rules for cover are out (in Fields of Fire) there is more than just the basic +4 modifier. Optimize your position and maximize your cover.
6. Cover your buddy's ass (not like that, you perverts!). Suppression fire is your friend. It allows you to keep your opponents' heads down while you do something else. And if the cretin is dumb enough to step out into the line of fire, he gets hit. Many times, its easier to hit with suppressive fire than it is with regular fire. You generally hit with fewer rounds, however. Makes sense. Also, overwatch is important. Control your field of fire. scan it, and if anything moves, vape it. This works well in Shadowrun because held actions are already written into the rules. Also, use bounding overwatch. This is a combination between principles 1. and 6. Basically, it's this. When you have multiple operatives, one or more take up overwatch while the rest move forward. Once they get forward, they in turn take up overwatch while the ones who were on overwatch before move past the new overwatchers into a position even farther to the front, and the process is repeated. Somewhat slow, but at least you have a better chance of being alive once you get to where you're going. The principles of overwatch and suppressive fire go well together. For example, operative A maintains suppressive fire on a doorway (behind which hides a cretinous shadowrunning slimebag) while operative B gets in position unmolested and takes up overwatch on said doorway. Then operative A drops the suppressive fire and gets into cover (also, op A could fire his weapon empty, so that satisfying "tink" of the empty magazine lulls the runner into complacency). At this point cretinous shadowrunning slimebag thinks to self "Ha! Goon is sans ammo! Now is the time to make my move!" Wrongo, >dead< cretinous shadowrunning slimebag. Keep in mind that since the runner's head was pinned down, he may not have seen op B move up (the ideal situation) and may be taken totally by surprise (ouch, no dodge). You may want to just take the shot and allow the runner to dodge as a surprise test may not go favourably for the goon. It's up to you.
7. And speaking of surprise... Ambush is a good thing. Even your typical corp goon with Reaction 4 and Threat Rating 2 rolls 6 dice, target number 2 (as they are laying in wait), for an average of 5 successes. The chromed street monster with wired-3, yielding reaction of, oh, say 12 rolling at T# 4 is only going to get 6 successes on average. So even a wimpy corp goon can give a Sammi a run for his money under the right circumstances. Imagine what a SWAT trooper with Reaction 6 Threat Rating 3 would be like. And even if the Sammi beats some of them, he may not beat them all. Also, the bonuses to Reaction from BattleTac are added to the dice rolled for surprise tests, so this can get ugly when facing well-equipped foes.
8. Throw in all the other stuff from various sources as well. In the Lone Star Sourcebook it talks about Astral backup whose sole purpose is to hose enemy mages by forcing them to turn off locks/foci/etc., banishing or controlling their spirits or elementals, and killing their spells before they reach their targets. Fields of Fire has stuff on tactical computers, target designators, etc. that can make any runner's day quite unpleasant.
9. Concerning cover. A useful rule for both PC and foe is to allow inadvertant hits through cover. The way I run this is as follows: Say your target number to hit someone with your Ares Predator is a 6 without cover. Say the target is hiding behind partial cover, for a total target number of 10. If the shooter rolls no successes at the high target number, but would have hit without the cover, the shot still hits, but the target has the benefit of the cover as armor from the hit. In some cases (where the barrier rating of the cover is higher than the power level of the shooter's weapon), the shot would be considered a miss. Say in the above example, the target foolishly takes cover behind a bunch of empty 55-gallon barrels (barrier rating of maybe 4). The shooter rolls a 2,2,3,5,8, and 8. None hit the target alone, but the two 8's would hit otherwise. Thus, they actually do hit, but the power level that the target would resist is only a 9 - 4 = 5 before the target's armor due to his cover. This kind of situation is realistic and makes people think about what they are using for cover. It's especially useful for suppressive fire. You will rapidly see players taking more care in what they hide behind.
10. Limit your opponents' visibility. Smoke and flash grenades are wonderful for giving you an extra little edge, especially when trying to move into a better position. Under cover of smoke, operatives may be able to move totally unmolested into positions that offer far better tactical advantages.
11. Position. Optimize it, as I said before. When working in conjunction with others, try to get the targets into a cross-fire situation. To clarify, cover is often only uni-directional, meaning that if you were to shoot from the side, say, instead of from the front, the target may have less, or even no cover. And in this situation, with multiple opponents shooting at you with less cover mods, you will eventually run out of combat pool and get hit. Also, cover that actually is omni-directional often limits your abilities to escape. If the shadowrunner decides that his position has become untenable and tries to retreat, he may need to go over or through his omni-directional cover, which will probably be considered difficult ground, thus making it harder to dodge effectively.
12. Stay out of trouble. Once the shadowrunners enter someplace where they are likely to meet opposition, that opposition should be smart. Instead of charging in and trying to hose them down, have them wait, send a few guards around in behind the runners, lure them into areas that you have control over, that limit their escape options. Herd them into natural cross-fire areas. Control them and trap them.
13. Speaking of traps...Never underestimate the value of an anti-personnel mine. If the SWAT or security forces know that the party is coming or have the time to deploy them, traps work well, especially when used in psych-ploys (attack the runners, leaving a moderately obvious avenue of escape that is booby-trapped like all get-out). Even in improvised situations, a grenade and a length of wire can be a moderately effective trap, especially when deployed to cover a retreat that may be followed up.
14. Divide and conquer. To keep from getting flanked into a crossfire situation, exploit every opportunity to separate the opponents' forces into smaller groups that are more easily dealt with.

Also, I've said it before and I'll say it again, modifiers are the life-blood of the Shadowrun game system. If the only modifier you remember is the -2 smartlink mod, it's no wonder combat is over so quickly. Even just cover, movement, range, and visibility can totally screw a target number and push it into the double-digits. In combat, you tend to spray a horde of rounds in your opponents' general direction with little or no effect. The exceptions to this are ambushes and combats that take place at incredibly short range in open terrain. In the long run, you'll probably roll less because you won't have to roll the NPC's body-resistance and knockdown so much :)

The final thing that you need to take into account is what you ultimately want out of your game. If you want cinematic, by all means go with the quick-and-dirty option. But this has its disadvantages as well. Generally, normal and even buff goons will be meat for the runners. Your players will probably go through your NPC's like papiere-mache, a situation which often leads to PC vs GM power escalations that rapidly get out of hand. On the other hand, if you play your goons smart, remember your modifiers, and go with a higher level of realism, even weak goons can give experienced runners a hassle in certain situations. Then, the runners have to rely on planning and coordination rather than brute-force to succeed, which I always imagined was the point behind running in the first place. The trade-off here is more stuff to remember or keep track of. With practice, though, this gets easier with time. In the abstract, one system is no better than the other, it's just a question of gaming style. I pride myself on the level or relative realism (barring the initial suspension of disbelief required to even play the game) that can be achieved. I think it makes the game enjoyable on a more reasonable level.

If for no other reason, give some of the subjects mentioned herein a try just to see the looks on your players' faces when they are vastly outclassed by weaker foes with a little bit of tactical know-how.

Above all, enjoy and feel free to comment or request elaboration/clarification on whatever.