http://evilempireguild.org/guides/acstamina.phpThe link above has numerous guides to various topics such as threat, defense, stamina/avoidance, Mitigation, Crits, and many other things that I go back and look at when I need to reconcile with tanking, but has loads of information other classes might like to know
(warning, lots of reading and math abound in the guides... don't say I didn't warn you)