I four table .02/.05 rush profitably. And, what you want to be able to do is understand odds
really well. I calculate my odds in a second and then I just have to remember the play that's happened up to that point. Honestly I'd recommend that you become really familiar with pot odds
/implied odds, and then just get good at calculating it quickly... And that come from experience and reading lots of books/articles... Plus everything else everyone else has said. :=)
Also, play in position... I can't stress how important that is.