This is the Army’s marksmanship manual. It’s a long read. I challenge anyone to stop shooting until they have read it cover to cover. I did, and the first time I went out and shot afterwards I center punched the X in the 10 ring.
http://www.saveourguns.com/Ar_Marks_...rain_Guide.pdf
If nothing else you will understand the fundamentals and how to apply them in your style of shooting be it action or bulls eye.