Don't know if this has been posted, but it's a very good defending tutorial, for those still a little unsure of how TD works or even if you think you've mastered it :
YouTube - Fifa 12 | Defending Tutorial | How to defend in Fifa 12 | HD
That's pretty good. His points about switching players frequently to maintain defensive structure, and playing with anticipation, are I think the most important ones. The secret to effective pressing is anticipating the next available option(s) before the pass is played.
This might be what I'm enjoying most about FIFA12. I'm finding defending almost as much fun as attacking. It's still very difficult to protect your penalty area, but as others have mentioned, it is very satisfying to pressure an opponent into a mistake or interception and win the ball back high up the pitch.
Here's one I just had, playing an exhibition as Derby against Crystal Palace. I've resisted the temptation to drop the difficulty level, so this is still on Legendary, although I've lowered the half length from 15 to 10.
The Palace CB just dis-possessed my attacker and is bringing the ball out of defence. Unfortunately there's not much down the line for him, the nearest teammate is marked, and he can't squeeze the ball through to his forward. So he ends up offloading the ball backwards to his supporting fullback, so he can return to position.
The fullback's immediate forward options are marked. However, there's another teammate in obvious space infield... but I've spotted this too. I use the right thumbstick to switch to the player marked in blue...
...and by the time the fullback has turned inside, I've already shut off that option:
At this point I'm now also holding [RB] (teammate contain) to start to pressure the fullback, who has had all of his options closed off. He turns and dribbles away under pressure. Still controlling the player further infield, I leave the first man I was marking and push on further to now press the centre-back, closing that option too:
The fullback attempts a rushed pass back to his goalkeeper which, on this occasion, is sliced inaccurately out of play for a Derby corner:
I'm finding it very engaging to try and anticipate and block the passing lanes in this way, it's a lot of fun.
I'm also finding that the CPU is able to consistently match me on the possession stats - in this game Palace edged it with about 53%. Which is nice.