Learn to read the defense. Their alignment can normally give you a good idea what coverage they are in. If you can guess what coverage, you can attack the weak spots of that particular coverage, and hot route to exploit them.
Read how the defense is lined up. If they have 6 or 7 guys "in the box" then don't try to run. Use quick passes. If they have only 3 or 4 guys in the box, then run the ball (even on 2nd and long)
I normally don't call a "play" so much as I call a formation. I have a custom playbook with audibles for each formation that are meant to beat certain coverages. I will audible into a play based on how the CPU defense is lined up/what coverage I think they are in.