Number 5 - Push ups: Body weight exercises are perfect when you are working out at home, but don't forget them as a way of adding variety in the gym. This is an exercise with loads of variations - you can do them with hands close together, out wide, in a diamond, or beneath your chest. Other variations include decline push ups, with your feet raised on a bench or an exercise ball, or hardest of all, put your feet on a bench and your hands on an exercise ball.
Number 4 - Incline Bench Press: The number one upper chest exercise. You won't be able to push as much weight as on regular bench press, but these are essential for total chest development.
Number 3 - Chest dips: An excellent and under-rated way to develop the lower pecs. Why don't many people do these? Because they are so intense! If you find these too easy, add some weights to increase the challenge.
Number 2 - Flyes: These are a classic dumbbell exercise, requiring a smooth controlled action. Be sure to keep your arms slightly bent throughout the movement, and don't lower your arms too far.
Number 1 - Bench press: No surprise, the king of muscle building exercises had to be number one! However, in addition to being the number one muscle builder, this is also the exercise at which more people get injured than any other - the causes? Too much weight and poor technique. So to get the best from this awesome exercise, focus on technique, not just how much weight you can shove around.