The Macedonian Centurions strategy.
The Macedonians collection of civilisation bonuses provides 3 which will directly effect the centurion, +2 piercing armour for academy units, +2 sight range for hand-to-hand units and x4 resistance to conversion. The advantages of this strategy are that it is relatively cheap to pull off, especially compared to something like heavy horse archers or elephants, the food cost is 10 less than 2 legions, the gold cost is 10 more. The upgrade is quite pricey, at 1800 food, but spent at the start of a DM it's quite definately worth it. The centurion (when upgraded) has the most damage of any non-siege unit, and is only 4 off a ballista. They alos have quite significant melee armour and a pile of HP. Their greatest weaknesses are siege, heavy horse archers and carthaginians, why? because the carth cents will beat them by about 4 HP and the elephants, en masse, can certainly contend with them and the trample damage, if the cents are surrounded would certainly kill many off. Siege, particularly ballistas/heliopolises are also a threat because they move so slowly - this can be countered somewhat by the macedonians cheap stone throwers, but is still a pricey thing to try and stop. Catapaults can be defeated by the application of a few scouts, but by the time you notice that the enemy have cats and get a stable and some scouts and make your attack, most of your base will be a big pile of splat. for these reasons the strategy works better in no siege games. Horse archers are the other threat since they can be used in very effective geurilla tactics, picking off 1 or 2 cents and then retreating - they also have the most damage of any archer and the second most HP. The best counter for these is some Horse archers of your own, but this can REALLY wipe out your gold reserves. The greates weakness of the strategy overall is a rush, since it take 2 upgrades to get up to a proper strength.
So, how do you pull it off?
First, grab 2 of your villiagers and put up 2 new town centers, grab the 3rd one and put him building academies - maybe some in an open space, just to stop the enemy getting it, also lay out a few around your base in a semi-circle. Set your new TC's building ~ 10 villiagers each, send the first 2 or 3 to help build academies, then set one on houses, set the ones who were finishing the TC's onto academies and the next 1 or 2 that come from the TC's. Grab the next one and set up a Gov't centre and market in your base, and the next one 2 storage pits. Select the first academy and do the phalanx upgrade, start punping about 10 hoplites out of each academy as it comes us. Set the next villiager on houses also, and grab the next few onto acedemies. Another onto houses and then the next few to start putting towers wherever you want out in the field and just behind the semi circle of academies - make sure these go right around your base. Whilst all of this is going on, nab you your Gov't centre and run the aristocracy upgrade, then the cent upgrade as soon as it's done. The coinage upgrade at the market and metallurgy + iron shield at the storage pits respectively - once these are done chain mail + tower shield. As soon as all your houses are built, find a site, preferable inside your defensive 'wall' of academies and put up a granary in the middle with your govt't/storage pit guys, after running the irrigation upgrade at the market have the go to farms, once you have 200 pop worth of houses ahve them join in, split the guys who were building the academies + towers between a nearby (NOT the one in your base) gold mine and more farms. Grab one villager and send him to put up a TC + some towers near another gold mine a distance away. Don't forget to upgrade those towers & ballistics/alchemy at the Gov't centre. By now each academy should have ~10 cents around it - presto, one defense. Try to leave a few cents around academies at all times and put some towers up in your town centre. Don't get more than 40 / 50 vills - 150+ cents is a bad thing to mess with, and allows to you have both an offensive army and a considerable defensive guard.
Split the cents into about 3 teams, and have them work together. If you can have an ally target-spotting all the better, otherwise just use your +2 sight range scout. In a large masse such as the ones you'll be using cents need very little micro management, except to have them try and chase after villagers or to direct them at the enemies towers rather than houses. The can also be used VERY effectively if you do a 2-pronged attack - most enemy forces need to work as one to be effective against cents, but just 12-20 cents can be very destructive, whilst the main force keeps the enemy interested - a 3 pronged attack if carefully orchestrated can take out a base defended by Horse archers.
Centurions are not alien to Geurilla tactics themselves - sneaking about a dozen cents along the enge of a map behind some trees into an enemy base, you can whipe out 1/2 an economy before the enemy know what's going on - it can also give the impression of a larger attack to come and stop your enemy attacking you.
A line of ballista towers is best tackled from an end if at all possible - as it gives less of them an ability to fire at you.
If you're making a full scale attack on an enemy base and stop a pile of villiagers mining away busily on the way in, grab 3 or 4 cents from the back and direct them at the villagers, most players will be so busy trying to fight your force off that you can cut off his gold supply and kill 1000 food worth of villagers all at once.
Once you know that you are unlikely to be attacked, or you have piles of towers up, cents some of the defensive cents to refresh your forces - 30 brand spanking new centurions can really add momentum to your attack, and have a psychological effect.
The strategy is very good in foot wars - particularly sensible ones that allow towers, as the cents can destroy the towers with few problems and the only units that really pose a threat are carth cents or masses of choson legions - 100 cents can kills 200 cho legions if they come 100 at a time, but not if they come 200 at once. The only other weakness I've found is a minoan composite bowman rush, it only takes 1 to wipe out your entire attack before it's even started - if there's a minoan opponet, hope that you aren't placed next door - or that you are playing a proper player who doesn't rush in under 3 minutes for a cheap win.