Make sure you don't leave holes in your defence by over-using the [] button though, a good player will spot this style of defence and will have an OM player hanging about near the empty areas while he attacks via a different path.
Using the [] button will cause defence to leave their line, all he then has to do is whip the ball to the center and there could be a nice gap for the OM or CF to exploit.
My favorite form of defence is to make sure your back 4 don't go far off their lines (use the defence setup screen to set the style of defence and man-marking). When under attack, move your highlighted player so he blocks any path to the goal for the forward (keep your man between a line from the attack and the goal, and also try to limit his options on passing), hopefully forcing the forward to either pass or make a hopeful run.
If the forward commits himself to a run on goal you have a chance here to use X (and [] if he's limited his options to a straight attack) to do a number of things.. Your defender could take the ball, or block a shot, or simply crowd the attacker out.
If you end up in a goalmouth scramble (heart failure time!), then throw bodies at the ball, they'll do a good job to block anything, but use X to clear as soon as you can, unless you are confident enough to pass the ball out and go for a break