The thing that helped me most and I posted somewhere else is to pre-exhaust the chest. I use a pec deck, shoulders against the back rest and ass at the very front of the seat (makes it like an incline fly) Do 3-4 sets, fairly heavy but with a full and slow range of motion.
Then what worked for me was inclines, flats and declines (bar or dumbbells, you pick), 3-4 sets, 8-12 reps every chest day. Start with a new angle every week. Bring up the whole chest and the upper pecs will look fuller.