There is very little left that can be exploited in lieu of straight counting, but there are many things that can be exploited in conjunction with straight counting.
The best way to learn it, in my opinion, is to get a shoe of cards, mark them up as needed, and practice- see what riffling, stripping, and cutting do to the location of the cards and the order of the cards. After that, it's just a matter of recognizing exploitable shuffles and doing the math.