don't try to learn them all, you'll do a mess eventually. There are only few of some importance.Try to learn those from older guys,or from FCTM's.
As I was once told,it's safer to memorise as little as possible of the nonessential things.Otherwise,in a emergency situation,or under stress you'll be more inclined to make mistakes.
For a great collection of rules of thumb check this
http://www.flightinfo.com/rulesofthumb.asp
Try to take only what you need .Don't try to memorise too much,cause you'll end mixing them
