The Weider Principles, a list of weightlifting truisms gathered and honed by the father of bodybuilding Joe Weider, have stood the test of time.
We highly recommend that you use them, too, as you learn and advance your muscle-building efforts.
Devote portions of your training year to specific goals for strength, mass or getting cut. This can help decrease your risk of injury and add variety to your routine. Cycle periods of high intensity and low intensity to allow for recovery and spur new gains.
Incorporate a diverse selection of variables, such as set, rep and exercise schemes, into your workout. Bodypart routines should utilize both mass-building multijoint moves and single-joint exercises.
Experiment to develop an instinct as to what works best for you. Use your training results along with past experiences to constantly fine-tune your program. Go by feel in the gym: If your biceps just don't feel like they've recovered from the last workout, do another bodypart that day instead.
Constantly change variables in your workout -- number of sets, number of reps, exercise choice, order of exercises, length of your rest periods -- to avoid getting in a rut and slowing growth.
Don't allow a given muscle to rest at the top or bottom of a movement. Control both the positive and negative portions of a rep and avoid momentum to maintain constant tension throughout the entire range of motion.
Train one bodypart with multiple exercises (3-4) before you train another. The "flushing" is your body sending a maximum amount of blood and muscle-building nutrients to that area to best stimulate growth.