One of my top books I use to help organize my youth football practices is the Complete Book of Drills for Winning Football by Micheal D. Koehler. It has over 350 football drills in offense, defense and special teams; agility, quarterback, running back, receiver, offensive lineman, d-lineman, linebacker, tackling, defensive backs, and team drills.
It has great diagrams of the drills, with coaching points, purpose and detailed explanations of the football drills. I highly recommend Complete Book of Drills for Winning Football.
Play for Fun and Winning is Funner!