Late Game

Once in the money, remember the premium for winning. When short stacked avoid the temptation to hope the other players will take each other out. They’ll be thinking the same and will happily watch you lose on the blinds. I advocate a more aggressive approach. Look to double up with all-in plays based on any reasonable cards. You’ll be surprised how many times the other players fold, and more surprised how often you will win with average cards. This does not mean go all in with 72o, but A8o is not such a bad hand when the blinds are killing you.
If you are ahead, keep on the pressure. Respect big raises, but attack calls, especially where both opponents have put in money. By small raises, you can stimulate betting between them and get into the heads up stage even if you lose the pot.
As with all heads-up play, aggression tends to be the winner. On a straight show down, most hands dealt are a coin toss so the winner will be the player who wins with the most bad hands, not the one who gets the most good hands.
Some strategies advocate raising 80 to 90% of hands. I’m not sure if this is true in no limit STT’s but over a long period of time, success is based on the number of hands you bluff rather than the number you win on merit.
Develop your own preferred style. Some players prefer numerous all-ins, others like to use smaller non-fatal raises. The important thing is to be comfortable and consistent with your strategy, and to monitor if it is working. If your records show you get in the money more than 50% of the time but you are only winning 10% of the time, your heads up play is almost certainly too passive.
PS - I find this advice easy to give but incredibly difficult to follow. You’ll really have to grit your teeth with this one!