Broad strategies for various stages of a tournament
The following depends on your definition of tight, loose, aggressive, etc. If your tight is too tight you won't pick up chips when needed. If your loose is too loose you're going to be leaking chips like the Titanic. This greatly depends on you actually having different styles you know how to play each of them well.
At the very beginning of a tournament (say rounds 1 and 2), play very tight, but aggressive when you have a premium. Lots of all-inners and/or people wanting to chip up early so are willing to play loose.
Then after those first 2-3 rounds, you want to switch to your normal TAG style. Play TAG until one of two things happens, you get down to a low stack (say 20-30 BBs), or you amass a large stack (say 80-100 BBs).
- If you're loosing chips while playing TAG because you're not getting enough good hands, then loosen up your hand ranges and play a little less aggressive. You want to be seeing more hands, but you want to keep the pots lower because you don't have the chips to be throwing around in big pots and missing your hand. You can even throw in some well-timed bluffs if that's in your skill-set (see https://www.cardschat.com/forum/learning-poker-57/bluffing-101-a-363335/ for a lot of tips on bluffing).
- If you're sitting on a medium range amount of chips, continue playing how you've been playing. You're doing good enough to last a while in the tournament without needing to risk more chips.
- If you've got a large stack then continue playing tight, but play much more aggressive. Play large pot poker and try forcing players out of hands or getting the small stacks to go all-in on your good hands to take them out of the tournament. Throw in bluffs when appropriate.
On the bubble (actually a few places from the bubble) and short-stacked, you want to tighten up. You need to survive until the money and then open back up if you've survived. If you're large-stacked then loosen up some, you want to be taking people out of the tournament to get into the money.
At the final table, treat it like a 9 player sit-n-go and not like a tournament. If you're not good at sit-n-gos then I suggest playing quite a few and developing those skills if you want to be successful at final tables.