The best thing to do is time your tackles. This is very important otherwise it could result in a foul and a yellow/red card.
If you hold sprint (default r1) and X, this makes your player follow the ball where ever it goes and is pretty useful when the opposition is running with the ball in front of you. This only works when you dont have the ball, obviously.
Otherwise, when the opposition is running towards you and you are face to face, try the slide button (O), but if they move quickly, chances are that you have a card. Do not do it close to your box and especially not if you are the last man.
If the opposition is one-on-one with your goalkeeper press triangle to bring him out. Timing is CRUCIAL otherwise they dribble to the side your goalkeeper is beaten and they score. Press triangle when the other player has just kicked the ball infront of them, just as they do when they dribble. ie that get the ball > touch it forward > this is the point where the ball is the furthest from them and they have less time to move it out of the way from your onrushing goalkeeper.
Hope this helps.
