It is believed by many that low reps with heavy weights are best for building muscle size and strength and that higher reps with light or medium weights are best for building muscle stamina, muscle endurance and muscle definition.

Low reps would be between 4 to 8 reps. Medium to high reps would be between 10 to 15 reps. If you are new to weight training for building muscle, a good place to start would be to pick out at least 1 exercise for each body part and do 3 sets of each exercise.

Start out with a light weight for a good warm up and do 15 reps for the first set, then add some weight and do 10 to 12 reps for the second set. Finish off with a heavier set for 8 to 10 reps. Add the weight in even increments for each set.

The key is consistency. Try to come up with a work out routine that you like to do and stick with it. Make gradual adjustments over time until you develop the perfect routine.

An extremely important thing to always remember is to warm up sufficiently at the start of your work out. If you do not warm up first, you run the risk of injury. One good way of warming up is to start out with a light weight and do higher reps for the first set of each exercise. Add weight in even increments for each additional set.