Learn to be still! I can't tell you how many folks I've taken out that don't really understand what it means to sit still.
I always asked each one when approached about taking them out, "Can you sit still?" and they almost always answered "sure, not a problem!"
There only one or two over the years that I'd go back out with. The others seemed to always be looking for something, eating a snack at the wrong time and place, scratching themselves or just fidgeting.
So in a word, "sit still" move your eyes more than your head. If you need to move something else use your eyes before you move anything else and when you do move, move VERY slowly.
My 2 cents worth.
God bless,Mudd
PS If you can't sit still, use a blind.