In short :
1. Early stage (75 BB): Tight as possible. Play only premium hands, avoid speculative hands like suited connectors, you can add some small PP and try to hit a set and possibly stack someone off. But only if you can see a cheap flop, dont throw your chips away.
2. Mid stage (20-30 BB) : Tight as well, but add some button and late position steals.
3. Late stage (5-15 BB): Loosen up. Be aggressive,but selective. In general, you should shove a lot, but almost never call a shove, let's say 90-95% of the time. Sometimes even aces should be folded, especially on the bubble.
For example :
On the bubble :
Big stack shoves, has you well covered, you hold aces, but there are some small stacks i.e. 700 and 900, and you look healthy with let's say 2500. Easy fold.
Learn some basic ICM calculations.