1.) Incline the bench: In order to recruit the upper pecs you should make sure the bench is at a 10-20 degree angle. By elevating the angle of the bench whilst continuing to push directly up in a straight line, the bar or dumbells should naturally finish above the upper chest concentrating the weight on this area.
2.) Perform reverse grip presses: When performing a reverse grip, your palms should be facing your chin. The reverse grip bench press can be done on a flat bench with no angle. The range of motion starts from directly above your upper chest and outwardly arcs towards your lower chest on the decline. You should finish directly above your upper chest on the incline which again concentrates the weight and muscle squeeze on the upper pecs.
3.) Perform incline negative reps: There are two main phases involved with bench pressing known as positive and negative motions. The positive phase is the press, and the negative is the return movement towards the chest. Ensure you recruit the services of a spotter for this movement for when you reach failure. Negative reps are very beneficial when your muscles begin to fail and you can no longer perform the press (positive phase) as they allow you to continue stressing the muscle when you would ordinarily fail. You can also increase the weight you place on the bar and just focus on gradually lowering the weight to your chest, and utilising the spotter on the press (positive phase) if you are unable to get the weight back up.