Middle MTT Play
After you have given the fish a chance to throw away their chips and you are at the table with fair and solid players, now is the time to loosen up and play your regular game. Your hope at this point is to rake in a good number of chips, so that you make it to the final tables with at least the average amount. Middle stages are also prime time to bluff at a few blinds. You have two things going for you in this case. First, as more players are eliminated, the thought that “we dont have too far to go to make money,” begins to settle in on everyones mind. Many players will completely lock up as they move further into the tournament. Secondly, you have hopefully gained that “rock” tight image. A bet or raise from you will be respected. This translates hopefully into a few stolen blinds.
A word of caution: you're still a good ways off from the money, and so a stone cold bluff with rags would not be advised. However, QJ, offsuit in late position where you only have one caller, or the blinds to go might be worth a raise.
In summary, middle tournament play should resemble your regular style of ring game play. You're looking to gamble a little and collect enough chips to be a force at the final tables. If you bust out in the middle stages with good cards, then so be it. Better to lose it on a good play, than to make it to the final tables, short stacked and get blinded away to finish just outside of the money.