People have been trying to build big, strong, thick, pecs for generations. The problem is that these same people too often allow their egos to intervene. In other words, they become too concerned with lifting heavy poundage as opposed to concentrating on feeling the muscles of the pectoralis major and the pectoralis minor work.
The key to building a full, shapely chest is to hit the muscles of the area from a variety of angles. Repetitions should be performed in a slow to moderate, controlled speed on the contractions and the negative portion of the movements. Focus on squeezing the pecs at the top of each repetition. Use a combination of high reps--light weights with low reps--heavy weights. High rep sets should be between 12-15 reps. Low rep sets should be between 4-6 reps.
The pyramid technique of training is an excellent one to apply to the flat bench exercise. Try doing 6-7 sets consisting of a warm-up set with light weight for 12 reps, followed by a set with 10 reps, then 8 reps, then 6 reps, then 4 reps, increasing the weight each set. Then decrease the weight by 25-30% and complete 1-2 burnout sets for reps.
Your other chest exercises can be approximately 3-4 straight sets. Try a drop set occasionally on the last set of each additional chest exercise. As a general rule of thumb, stick to the basic chest exercises: Flat Bench, Machine Bench, One Dumbbell Movement (Flat, Incline or Flye). Finish off with Peck Deck or Cable Cross-Overs. If you want your chest to reach its maximum development, you must implement drop sets, burnout sets, super sets and/or forced reps. The number of sets will vary from person to person. I suggest 2-3 different chest exercises for the novice trainer (totaling 9-12 sets) and 4-5 chest exercises for the advanced trainer (totaling 14-16 sets). Rest about 45-60 seconds between sets to keep the intensity high. Stretch between every set for about 10-15 seconds. This strategy will help you to break through plateaus and super shock the pecs into continued growth.