I always had this problem, still do to a certain extent, i think the key change in my play which helped the most was restealing, this is especially true in the later parts of a mtt, for an example say average stack is 40000, bb2000, and you are in big blind, with 48000, and a 54000 stack who you have seen doing many positional steals (1-2 an orbit) raises 3*bb from the hijack, just shove allin with any two cards, more often than not they will fold, as they dont want to tangle with another above average stack. Don't do this to any stacks which are about below average, as most of these should be pushing allin preflop, so the standard raise by them signifies strength and will be called.
choose the people who you are going to steal off wisely as well, usually average stacks are the best, and don't be scared of pushing all your chips in preflop straight away, do this a couple of times on a steal, and then tighten up and then do the same when you get a big hand, never do a standard raise with a big hand after being seen pushing allin preflop, as it will look stronger and won't get the action you want, which can also be used a
bluff, ie. do a standard raise after a few pushes with ATC.
These are just a couple of the things which have helped my game, and a few nice suckouts when the resteals have gone wrong always help.
shandy