Adding banded tension to your shoulder work is guaranteed to trigger new hypertrophy gains. Just grab a couple of resistance bands and wedge them under the bench for overhead dumbbell presses.
The key is to lift the dumbbells all the way up to the top and hold them there for a couple of seconds in the contracted position of each rep.
With the squat, you want to break from the knees and hips at the same time. This plyo drill can teach the correct movement pattern and fix bad patterns.