During the earlier stages, tight is right is usually a good strategy to follow. You shold play more cautiously when blinds are still low. You don't have to get committed to pots with marginal
hands like A10, QJ, KJ, etc. Not saying not to play them, you just dont have to and you don't have to get your stack in with these hands. Look to limp in with small-mid pairs and suited connectors as you'll be getting great
odds to hit your hand. To vary your game, raise with these hands if you're first to open in mid-late position.
OBV, with higher blinds you're going want to open your range and play more marginal hands. Especially if your stack is dwindling. The marginal hands you tried to avoid playing for stacks early on are (sometimes) going to be the hands you want to play for now. Raise/3-bet shoving with QJo, etc. These are the types of hands that may make or break your tournament, but they're also the hands that'll determine if you'll min-cash or make the final table.
When blinds get bigger, you can lower your raises to 2.5-3x BB instead of standard 3-4x BB. This is just as effective, but you save chips if you need to fold to a 3-bet or anything. Really good if you're blind stealing, the 2.5x raise is really strong. A lot of the time, when blinds are really high, players arent going to want to play weak hands OOP and will give it up. And when they do raise, you can fold (if you're weak) and not have risked that much. Sometimes, a smaller raise is just as effective.
...Blinds are 600/1200, a raise to 1250 might work, too...depending on the player.
Cliff notes:
-Tight early/avoid marginal hand situations
-Aggressive late/be prepared to play marginal hands for stacks if you need to
-Raise less when blinds are high.