Briefly, notes from Crowton (I think back from his Louisiana State days) on what he tells his quarterback's to look for before the snap.(1) Scan the coverage. Is it man or zone coverage? Are there two safeties,
one safety, or no safeties?
(2) Check the perimeter and the edges of the box. How will I be protected?
Will I be protected?
(3) Point to the "hot" defender away from the protection call. You are
identifying the defender that must come to create a "hot" throw away from the
call side. This is vital if you do not have a built in "hot" receiver to handle
a 4th rusher backside.
Another common method (popular with the Airraid types) is to integrate the number of safeties into the snap count. I.e. "Go! 2! 2! Set, Hut!" This way the QB has to look.