DO: Start off by reading The Shadow Court (now out of print) and Book of Houses II sourcebooks. They'll give you -excellent- background material on the House you're playing. Also, if you're going to be playing courtly politics, read Nobles: The Shining Host (also out of print) if you can find a copy. While most of these customs aren't observed by the Ailil, it's good to see what the opposition believe in -- all the better to undermine it.
DON'T: Assume that you are playing the polar opposite of all that is good and right. While some comparisons are just, Ailil are not the Lasombra to Gwydion's Ventrue, nor the Sabbat to the Camarilla, nor the Shadow Lords to the Silver Fangs, etc. Ailil are very strange contradictions. They use Banality and Cold Iron as tools in their machinations, but they are still children of the Dreaming and very much interested, in most cases, in preserving the ways of Glamour. Many of them still believe in honor, albeit a twisted version.
DO: Determine what political camp you are in within the Shadow Court. The Shadow Court is -not- one big happy family working together to undermine Seelie rule. It has a legion of agendas, which range from merely restoring a balance between Seelie and Unseelie rule to destroying all Seelie rule and placing the Unseelie in permanent power to destroying ALL forms of government and allowing chaos to reign to annihilating everything Glamorous in one fell swoop with the hopes of returning to Arcadia through the backlash. There's more. Read the Shadow Court if you can get it -- I believe WW has it on their website as a Download. It's -the- reference you'll need.
DON'T: Fall prey to the assumption that the destruction of one's enemy is best served by killing him. The Ailil are leaders and heavily outnumbered in the war in Concordia. Every converted soul, particularly the ones that go undetected and have some power, is worth its weight in gold. There's a -reason- the topmost powers in -both- Shadow Court arts are used for twisting the hearts of others into the Unseelie ways of life. Your goal as an Ailil is to graciously help others fall from grace. Embarass them, foil them, seduce them, enrage them, and then when they are most vulnerable, show them a new way.
DO: Be subtle. . If you're a complete cartoon of a stereotypical bad guy, people won't care about you at all. Show them complexity and restraint, the possibility that perhaps what you're doing is right or that perhaps your hand is forced by some greater power, the possibility that you might actually know what love and compassion are and that you regret not being able to show such things to others, and they'll be eating out of your hand.
DON'T: Overplay that you're special. As far as anyone else is concerned, you're just from a smaller Noble house that few people have heard of. Most people should not immediately know that Ailil is synonymous with dastardly. Pretend like you fit in, giving only a hint of something beneath the surface. Too much and people will think you're a plotline or a ham and run away. Just a taste and they'll want more. Show up to gatherings, blend, socialize. Don't drop comments like 'When Winter comes, -then- you'll know the true power of the Unseelie Court' or 'Your Seelie ways mean nothing to me'. There's no way to seduce people when you're spewing bombast of that sort. Make -them- ask the questions about why things feel strange when a noble punishes a commoner and gently guide them along the path that you follow.
DO: Exploit class differences. Play nobles against commoner and vice versa. Chaos is your friend.
DON'T: Be so obvious as to get caught doing it. Use intermediaries and subtlety.
DO: Use the Dark Arts to make bad situations worse. Contempt is great when you want to see tensions already high exceed the boiling point. Delusion is a wonderful supplement that you can use to manipulate pawns into the right position without leaving trails leading back to yourself.
DON'T: Ever use them in a place where others will observe what you are doing. While the Mists cover them up somewhat, these are supposed to be -secret- Arts. In the case of Contempt, only use it in crowded spaces where your Bunk will either go unnoticed or where a Bunk is not necessary.
DO: Seek out potential converts for lots of one-on-one role-play time. People -want- to be swayed to the Dark Side. You just have to put out the proper bait.
DON'T: Spoil the chase by revealing too much too soon.
DO: Make time to make life miserable for the Gwydion. They deserve it.
DON'T: Forget that Eiluned is the sister house to House Ailil and that many of her servants can be seduced into once again helping you in your cause.
DO: Play the memory game. It's always powerful to suggest that you knew a character in a previous life, perhaps in Arcadia. Even if it's not necessarily true, suggesting a link from a prior existence establishes the precedent for you to begin knowing them again now. And if they bite the bait, who knows what you'll be able to convince them of.
DON'T: Allow yourself to be bullied socially. Ailil are leaders and their weakness centers around following their lessers or admitting they are wrong. Avoid these situations at all cost and remember that this House is perhaps the most proud of all Houses, including even the pompous Gwydion.
DO: Look at characters like David Bowie's 'Goblin King' in Labyrinth for a great idea of an Ailil ruler who uses seduction, half-lies, and occasionally force to get what he wants.
DON'T: Imitate the character Yrtalien from Jackie Cassada and Nickie Rea's 'Immortal Eyes' trilogy of novels. He's insane and not really Ailil anymore. If you've read the books, forget them.
DO: Gather allies and toadies. A number of commoners are just -looking- for something to do. If you can give them focus and show them a way or two to embarass the Sidhe, they'll revere you.
DON'T: Allow yourself to be the direct contact with your allies and toadies. If you're only one step removed from the poisoning attempt on the King, it's pretty easy to trace. Layers upon layers works best. Find yourself a trustworthy henchman or two, perhaps use Delusion's "Facade" power to make a mask for yourself if need be, and have -them- recruit more lackeys for uou.
DO: Occasionally use Banality to your advantage. You can use it in tests to defend against Cantrips if you read the Shining Host LARP book. Do so in cases where you may be in trouble if you fail. The Shadow Court is all about using Banality as a means to an end and this is one of its best uses.
DON'T: Let yourself play without reading the short stories at the beginning of both Book of Houses II and -especially- Shadow Court. -Very- good for getting the right mood for Ailil down.
DO: Play political intrigue like Malkovich or Close in Dangerous Liaisons. Refined, patient, and deadly, using words far more often than swords.
DON'T: Play political intrigue like any of the Brits in Braveheart or Rob Roy. Most of them get killed or worse and, really, you don't have the force to back your plays up the way they did. If you directly -tell- people they're the enemy, they'll behave like it. Instead, keep them guessing as to whether they fall into the category of friend or foe when dealing with you.
THE CARDINAL DO: Have fun playing the character. Remember that you're the villain and people really love having glamorous, complex villains. The more depth you bring and the more zest with which you quietly go about screwing things up, the more they'll love you.
THE CARDINAL DON'T: Ruin other people's fun. Forcing yourself upon them, using challenges to push them into action when the role-play fails, or otherwise pushing their concept in directions they don't want it to go will meet with resistance and resentment. Carefully feel out your potential conversions or enemies and see if they're really ready for that sort of role-play. If not, move along. There are plenty of fish in the sea and you don't have time to waste on the ones that won't bite.