My right thumb likes to shake a little when I fly, too.. Not a good thing! I find that it helps me to plan out exactly which manuevers I am going to do on a given flight, like "practice stall turns back and forth" or "do 10 touch and go's", so the only thing I am thinking about while flying is performing the required things. If I try to decide what I'm going to do on the fly during each flight it adds a level of stress.