I'll come from a different slant/avenue.
Playbooks. (Offensive and Defensive) Setting them up, streamlining them defensively and layering them offensively (with the appropriate %s on 1st and 2nd downs, particularly, is crucial)
Defensively, you're allowed up to 30 plays. (broken down by Goal-Line, Normal, Nickel, Dime and Quarter) First thing is you never want to use 30 defensive plays or really come close to it because a) you learn defensive plays slowly and do not want to be that divvy'd up and b) there's no way you'll get that many to be effective. You'll be a fireworks display on the 4th of July in a bad way every game with exploitable plays.
Any ways, get enough effective plays in each Defensive Set above and leave wiggle room. Clip out the bad ones in each set as you go along. Basically, pit the defensive plays against each other and come out in the end with your strongest possible defensive playlist circa 20 plays....in and around.
Ok, that's enough for one post. :)