One thing I started doing, and will continue to do permanently, is doing inclines first. My upper chest used to be very flat until I started doing all incline work first, then flat bench second. After starting that a couple years ago, my upper chest is quickly catching up with the lower, and it's becoming more proportionate.
This has another advantage too, IMO. It will allow your incline strength to almost equal your flat bench strength. I can now do dumbbell presses with the same weight that I use on flat presses.
Incline dumbbell presses are, IMO, a must. You should include them into your workouts. One training technique that you might wanna try is what's called reverse pyramiding, where you start out with your heaviest weight for low reps, then gradually work down to a light weight for high reps. So, you're dropping the weight, and increasing the reps for each set. And as you get stronger for that first set, you increase the weight. Before you know it, you'll be doing incline dumbbells with 100s or more. Be sure to warm up THOROUGHLY before that first set though, to avoid tearing something.
KB