There's really not much "skill" involved in Evo. There's only really 2 things you have to consider.
1) Can my opponent's character reasonably defeat whatever I'm going to put up. Basically this means don't put anything over a 5 Power against a 1.
2) Will whatever I'm sending up KO my opponent before he/she's had a chance to get his two wins. By having a chance I mean the two rounds in which your opponent is to put up their characters with the 6 pillz. If you want to put up 2 characters that would kill your opponent, and you're starting the round, then you should give your opponent round 2 and 3 and take 4.
While this seems like common sense, more often than not I've seen these two simple rules broken.
I put up another post a few posts down on things that shouldn't be done in an evo match. Read that and it should give you a solid idea.