A couple of things come to mind that I've seen repeatedly over the years. One is players who tend to have below-average stacks when they get into the late stages. The way to address this is to put somewhat more emphasis on chip accumulation / stack maintenance during the middle stages, and somewhat less on surviving. This doesn't mean going crazy, just shifting the balance of emphasis enough to have more chips when you get deep.
The other is working on your short-handed game. To win an MTT, you have to play down from full tales to HU. Since most of the final table is played with less than the full number of seats, being able to adapt to the shrinking table sizes is obviously important.