its cool that you can do loadsa different shots, but when should i use the differrent shot types, like X,0,{} and triangle? where should the opponent be? what are the used for? please reply soon!

i personally mix up my style and use them randomly, to confuse the opponent, but idon't think that you use them in an order.

most of the time i use square but sometimes circle and when receive serves i use X so i can get in a good position

I guess it all depends on the player whom you're playing. For starters, you don't want to be using the triangle button unless you've got pretty good stats at Lob&Drop (somewhere in the high A's or S) or playing against a weaker player. If you use it against the pros, they'll invariably get to it every time. The best time to use it is when you've played a good topspin shot (circle) and have forced your opponent wide. Then hit the down button and the analog stick and triangle in the opposite direction of them and you should usually time it so they can't reach the ball. I use topspin a lot (my stats in topspin are SS and my meet is SS, which helps place the ball right on the border lines). This helps win matches against fast players. My flat shot (square) is in the high A's. I use it seldomly (only when I serve, really, or when playing on grass because the ball skids past the opponent in no time). I rarely bother with slice. The only thing I find it good for is against Roddick. If you can get to his serve with a slice, it gives you that little bit more time to prepare for his next hit. But there's never any set formula for which shots to do at a certain point. It's all trial and error.