Huh.
Well, the main thing to know about playing Alex is to have good decision making.
The same sort of decision making that has you:
Saying something about your general skill level when asking for tips.
I mean, it makes a huge difference if your fundamentals are good or not, such as knowing how to hit confirm.
Asking someplace where people actually know the game, such as Shoryuken, instead of someplace random like here.
Seriously. So many people play games on easy around here, a developed and complex game like SF3 is a minefield for bad advice.
Knowing that Alex is low tier ... as such, there aren't many Alex specialists, but the people who do main Alex are more likely to help other Alex players. But, you're going to have to be not terrible before their advice will make sense.
The only guy I know of who still mains a killer Alex is Renic, though.