If you know its cover three, its a perfect situation to hit your outside receivers on the fade. You'll have to manually control the receiver and rocket catch, which takes some practice but if you're able to get comfy with that, then the cover 3 is vulnerable. Also if you come out in 4-wr set and have both slot receivers run slants, one of them should get open after the cross the middle of the field. It's the side where the safety is playing deep middle, so look for that opening in the zone.
Also, remember to step UP (move forward) in the pocket. Don't drop back too far or roll to a side, you have to give the receivers time to run the ball, so learning to move around in the pocket and getting those extra seconds will wreck havoc on the zone.