How to grip the bar: Your hands should be in the range of shoulder width. See what works best for you. You may find that a few inches in from shoulder width hits the inner pecs hardest. So experiment a little with the grip to find what allows you to get the most work and stress carried by your pecs.
How to do the movement: Bring the weight down to your chest slowly at the count of 1â€¦2â€¦ breathing in on the way down. Barely touch your chest before pushing the weight back up while exhaling to the same count of 1â€¦2â€¦ Focus entirely on letting your pecs do the work. Hold it at the top for a count of 1â€¦2â€¦while squeezing your pecs together. Then lower the weight back down to the same count while you inhale. Make sure this is all in one fluid, strict motion (no bouncing!).
Sets: This is somewhat of a dispute. First of all, get your form down with lighter weight. Then, use a weight that you can get only 6-10 reps on for 3+ sets for definition and mass. For more definition, reduce the weight and go for 12-15 reps and 5+ sets. For more mass, go for 5-6 reps and heavier weight for less sets. Just remember to get your form down good and always lift slowly and strictly to get the most gains, develop the fullest pecs, and avoid ripping or tearing muscles.
Note: To get full pectoral development, it's good to add incline and decline close-grip bench into your chest day routine. This will build and work the upper and lower mid parts of the pectorals, respectively. Use the same method as with regular flat bench close-grip bench. Build massive and full pecs!!!