There is a few schools of thought when It comes to defending.
There is the 'pro evo' method, which is basically running at the attacker with 2 or more players. So the attacker can't move/pass. This method can be effect but very very risky.
There is the 'back track' method, which is my favorite. It requires a formations with 4 defenders and 2 CM/CDM's. With the CDM's dropping deep the attacker will try and get between them (the CDM and the CB). Instead of bringing the CB out to meet him (which the player normally expects) you have a CDM close enough to grab the ball from behind

)), even if that doesn't work, you'd send the attacker off balance ready for the CB to tackle with ease.
Another method is 'the pounce'. I use this very often to great effect, but it requires insanely good timing. With an attacker running at you (CB), you either back pedal or hold your ground depending on the section of the pitch you are in. You carry on back pedaling until (just before) the attacker starts to sprint, then you 'rush' the attacker with one defender. Again this isn't easy to pull off but no very risky.
Some more tips,
Use any strength your defender has to either slow down or push the attacker off the ball.
A strong aerial presences is key.
CDM's are really useful for defending.
Don't bring your keep out unless he is (100%) the last line of defense.