If you are serious about Marksmanship, you need to read these four free chapters from Jim Owens "Sight Alignment, Trigger Control and the Big Lie". Within them you will find reasons for what you may currently do as well as other techniques that may help your shooting and instruction.
Good Luck!
http://www.jarheadtop.com/Free_Chapters_Blue.htm
I have his book on Leather Slings and Shooting Positions. Good stuff!
Thanks for posting this.