The
M concept in short.
M Is your stack devided by BB+SB+Ante(If Any). (Without going into effective M)
M = 20+ is Green Zone. Play TAG/LAG. Basically your preferred style as you can afford it.
M = 10-20 is Yellow zone. Play a little more loose than in the green zone, you need to stay ahead of the rising blinds. (Although I still stick to TAG here)
M = 6-10 is Orange zone. Now you are starting to be very close to be blinded away. Be prepared to go all-in with more marginal hands in a flop where you are IP and its folded to you. Basically be very agressive.
M = 5 or less is Red Zone. The only move you have is AI. Pick your spot with basically very very marginal hands if you are going to be opening the action. Basically go all-in in MP or better with hands like A5, A6, KT, 22 etc.
M = 1 you are dead (Dead Zone). Go all-in with any sort of pot odds, any holding when its folded to you and its Q7o or better. Etc.
That's the M concept. Now you also need to understand that people stack off pre a lot lighter. A lot of the time AK is a good hand to flip with pre. Playing draws agressively is good. Good idea to play tight at a loose table and aggressive at a tight table. You can use points such as bubble, raise in payout structure as good opportunities to amass some chips as people are generally tight then.
Hmm... that's my 2 pence. Dont want to rewrite Harrington here