Unfortunately, I think block shedding is more of a crap-shoot than anything else. Here's what I typically do:
When controlling D-Linemen at the snap, I generally use a the sprint button immediately, quickly followed by a finesse or power move, depending on that attirbute strength of the particular player I am using. Generally, it' is only moderately successful, but it does work well from time to time.
If you are speaking of shedding blocks in the open field (like chasing down the the ballcarrier with the middle linebacker), the only real piece of advice I can give is to play a good angle and try to reach the hole before a lineman reaches the second level to get a hat on on you. A combination of sprinting and strafing generally does the trick. (Just like they teach you in real football, try to keep your front shoudler even with the ballcarrier's back shoulder to reduce a cutback lane)
Once you reach the hole, shedding a lead blocker can be downright impossible, but if you have successfully reached the hole, chances are it'll be congested enough that another defender will be able to make the tackle, even if you're tied up with the fullback or a pulling guard.
Anybody else have something that works?