use push or fold with 13bb and less... Only raise 2.5bb against REALLY REALLY tight opponents..
personally I shove with less than 15bb's since with 15bb there is no room for play...
Just train a bunch with the ICM trainer and when you get gold you can read an article about the math behind ICM...
It's pretty much just:
- How good your hand is doing against opponents calling range
- How much % of the time opponent will fold to your push
this is basicly what it is + some value of chip calculations and vs the prizepoll.... It's way more complicated but this could be a simple model of it
and yeah for ranges calculations and stuff like that use the equialator or pokerstove or similiar softwares