1. Never fold PF
2. Almost always raise, 3-bet, and 4-bet especially if you and your opponent are deep.
3. Sometimes just call in BB for deception and to balance ranges if you and your opponent are very short (and it's not multi-way). Sometimes just limp if it's folded to you in SB and you or BB is very short.
4. On some aggressive tables you can trap and, protect your limping range from being attacked (if you have one) when your stack is just over the push-fold stage by sometimes including AA in your limping range.