Form is extremely important. Try to keep your traps and lats down and tight, your shoulders back and try to pinch your shoulder blades together, arch your back. When you bring the weight down you should feel a great stretch in the pec at the bottom of the motion. Don't lock out completely as this takes pressure off the pec and puts it unnecessarily on the elbow joints, triceps, and deltoids. Bring your elbows down toward your side, don't flare them out...doing this will put more of the load on the pec and less on the front deltoids.
Incline DB presses holding the DBs at a slight angle to my body (not perpendicular) at a higher angle (like 60 degrees) bench using the above technique made my upper chest grow noticeably in a few weeks time.
Good luck!