Basic MTT strategy:
1. Tight early, get reads on players.
2. Try to stay in the middle of the field but don't push yourself, the cards will come.
3. In the middle of the tourney keep tight out of position and open up to a range of
hands on the button and the cutoff providing you have a stack, I like to play a lot of suited cards and low pocket pairs from the button and CO, you can play them aggressively and passively, if you have a lot of limpers in the pots already, i'd limp too, if I'm the first in the pot I'd open up with a raise, if it does get to the flop I'll appear strong and I'll have a better idea of my opponent's hand.
4. Around the bubble play tightens up, take advantage of this, note who else is stealing around you, and who is playing super tight. Note the big stacks, medium, and small. Don't get into pots without good hands against the big and small, steal from the medium. Almost any position here is open to stealing except early position, from middle position on you can probably steal pretty well. Small stacks will fight from the blind so be careful who you raise into.
5. When you're ITM don't start playing junk and don't try and steal more, it will no longer work. The short stacks that squeaked by will start pushing with ace and king high, along with almost anything that you would consider raising with from the button with a stack (suited ace, suited king, suited connectors, low pairs.) call them down with good hands, AT+, 66+, don't play crap and hope they don't have anything. Even if they do come up with aces, they're still at risk if you're playing 66.
6. As the tournament dwindles down, everyone will be trying to consolidate chips for the final table, you'll see some tricky plays, some risky plays, and some stupid ones. Play will be looser, tighten up, don't expect to get away with a steal unless you have a good read on your opponent and their hand. Expect to be all in, probably multiple times unless you have a big stack.
7. If you make it to the final table, there are some good threads that you can find on here that can explain play there much better than I can. Check out the Golden Archive.
Good luck, these strategies and ideas are developed from my own play in tourneys such as the DD, I can't guarantee how successful they'll be in higher echelons of MTTs.