Bench-Press on Inclined Bench
The back of the bench should be fixed at an angle of about 30 degrees. Take one weight into each hand and lift them up to the clavicle level. Squeeze your pectoral muscles and straighten your arms upwards. Bend your arms in the elbows, and slowly lower the weight down to the chest level. Once again straighten your arms. This exercise can be done even with weight bar or on a gym machine.

Drawing the Arms Together on a Training Machine
This exercise will improve your decollete visually since it develops the inner tracts of the pectoral muscles. Sit on the bench, hold the handles (keep the elbows bent), draw the arms together till they touch each other. The movement should be done using the force of the squeezed muscles, not the inertia. Pause for a moment at the end point and then slowly return to the initial position. The steps of the exercise may depend on the machine type. This exercise can also be done on a bench (in lying position) with weights.

Arm Cross-Drawing on Blocks
This is another great exercise which aims at the inner chest area. Stand between two high blocks, hold the handles and draw the arms in (top-down) towards the thighs. Then slowly return to the initial position.

Bench-Press
This exercise develops literally every tract of the pectoral muscle, but requires some proper warm up. Lay down on the bench so that the rod is right above your eyes. Hold it with wide grip; lift the weight up and slowly lower it to the chest so that it touches your body roughly in the middle of the chest. Slowly return the weight to the initial position.