Tight in the beginning. Look for spots to bluff. Watch out for aggressive players who suddenly limp (probably has a huge hand) after 3x-5x raising like crazy. Try to increase your stack by 20% or so each round if at all possible. Remember the basics - do not chase a st8 into a possible flush, do not call every street with top pair/weak kicker. Remember the number one killer of MTT players - chasing hands. Gutshots are worthless unless incredibly cheap to chase! Open ended st8/st8 flush with top pair, not bad. Chasing one of 4 remaining 10's is suicide. Stay away from the stupid end of a st8 or flush.
Avoid going to war with with only one or two pair. Look for sets/st8s before calling 2/3 to pot size bets. You never want to get it all in without a made hand and/or 14 or more outs. Its not a cash game, you cannot simply re-load when felted. KEEP THIS IN MIND, but do not play scared.
Do not end up being the meat in a stupid-smart 3 way pot sandwich. If you got a decent hand, one loon betting into you like crazy and another just flatting the bets, look out - he probably has you both beat. If you flop da-nuts in a multi-way pot, slow play it only if the board is such that few, if any, cards to come can hurt you. Avoid the old limp-AA-UTG-hoping to be raised - you could end up in a 4 or more way pot with only one pair. Limp/slow play later, when you want one bigger stack to attack you.
At the money bubble, punish the short stacks. Try to avoid (at all times) all-in preflop with more than one opponent or bigger stacks. Play your position (more hands won nearer button than not). Do not raise 3x-5x. Raise the same amount each time (2-2.5x) - they will not know if you have AA or 56 suited. Eventually, you will 2x UTG with AA or KK and get some joker thinking he can run you off by shoving a far,far smaller pair. This is close to nirvana, provided your better pair wins, of course, lol. But if you 5x only big pairs, 3x only big aces, limp 22-99, etc, they are going to catch on and wipe you out. They will simply fold to your 5x, 3 bet/bluff your limp on big card boards, etc.
Watch out for players who just cannot fold A-K-Q-J rag suited when they connect (weak kickers). Your K-Q vs their K-2 when a K hits is a thing of beauty. Study up on pot control - this can not only save your chips, but allows you to win chips with moderate hands in moderate positions that you otherwise would not.
Most important of all, even more than having a monster hand - Shift gears - if you normally Cbet with air then check, try doing that when you flop a monster - they will think the Cbet was weak and might try to bet or think the weaker hand they hold is good. If you find an obvious bluffer, let him bluff - do not sandbag or run him off. Bluff him off doing that after kicking his arse once or twice! Raise UTG with other than AA/KK/QQ/AK/AQ once in a while, because they will tear you a new one on boards with all middle/low cards, as they "know" you only open UTG with those hands mentioned above. Dont do this with any two cards, but maybe try J-10 suited, 67 suited, etc, ONCE IN A WHILE!!! IF 3 bet a reasonable amount, flat it with these hands as you could flop a monster, or they could be 3 betting with junk. One time you flop a monster, slow play it; the next time come out firing like you are desperate to make them fold. Shift those gears!
If you make the final table, then open up, play it like a cash game. Above all else - have fun!