What I have done to really improve my passing game is pick 5 versatile pass plays, and only 5 plays, to have in my playbook. I practiced these 5 plays so that I know what different defenses look like against them, and what my progression should be against each look.
For example, one of my favorite plays is Mesh out of a bunch look. I can run this play and get a completion, no matter what the defense does, as long as I read the defense correctly.
Against zone defenses, the triangle created by the "X" "RB" and "B" routes should always give you an open receiver. Against man defense "B" on the corner route or "X" on the cross are often open.