These are the most important rules (to me anyways) for bodybuilding. These rules are a guaranteed way to grow, unless you have some bad genes in you.
Top 10 Rules
These rules have been compiled from a history of experience in bodybuilding. Follow this list of priorities and general rules for maximizing great results.
1 / Lift Big
Give your muscles a reason to grow. Don't do endless sets (or reps), be intense. Go heavy, but don't remain much longer than an hour. Train 3-to-4 days per week. Hit failure and make that last set count.
2 / Eat Big
Eat 6 meals per day. Don't be scared of fats. Cut junk food. You will crave chicken breasts, tuna shakes, pasta and chocolate milk.You must eat to grow. For gaining, take 20Cal/lb bodyweight daily. Get 30g protein per meal.
3 / Sleep
Recovery is key. If you're a meso/endomorph, get 8-9 hours a day; an ectomorph needs at least 6-7. You grow outside the gym, not in. What works and has always worked for me is getting over 10 hours of sleep.
4 / Water, Water Everywhere
Carry that gallon jug with you at all times. Drink 8 liters per day. Keeps you well hydrated so you can train at your best and have your caloric needs in check. If you care about how you look, just carry a bunch of water bottles with you.
Shove them in places to go to a lot. I carry about 3 in my car, 2 in my bag, and I have a surplus of it in my Fridge. Do not use tap water. If you do not want to buy water bottles, get a Brita water filter. It works like a charm.
5 / Commit
If you're not sick or injured, you must train. You start skipping ... you might as well forget those dreams. You must want to become that impressive physique before you can begin building it. Get yourself a reliable training partner. Do not train with a friend, because you will be distracted from your hard training. Try to get someone that is in your strength area, so that you do not have to keep changing the weights.
6 / You Aint Squat 'Til You Squat
If you have legs, a desire to grow and your back is OK, you must squat. Without the king of exercises, your growth is going to suffer. Squats develop more than just legs, they develop overall strength. You can take all the roids and supplements you want, and train with super high intensity, but if you don't squat, your 100% wussy.
Helpful Video: Alex Fedorov's Leg Training
Alex performing individual exercises - This no-nonsense training skips the chat and focuses on proper form and training hard. Watch these short clips as Alex trains his legs in the gym.
7 / Changeup Frequently
Change your routine around frequently. Every 3-6 weeks, vary the order that you do your routine, or change your whole style altogether. Try HIT, super-slow, negative training, high volume, etc. This is important because your muscles will get used to the workouts you do, and this way you will shock the hell out of them.
8 / Don't Overtrain
A good routine is brief, intense, and only has a couple exercises per bodypart. Limit the total number of sets you do. If your progress is slowing, you're getting injured or sick frequently, then it's time to take a break. Take 4-6 days off, and then go back at it. Don't be surprised if you're stronger after your layoff.
9 / Heal
Once you're injured, take a break. Lose 2 weeks training now, or prepare to keep those injuries forever.
10 / Form
Anyone can throw around the weights. Concentrate on good form, and then let the numbers follow. Get a full range of motion and be proud that you're one of the few who actually trains properly. Lessen the weight if you cannot keep a good form.
Those are the key guidelines you should follow, and those are the most basics. Follow these wonderful little rules and watch how much you gain. No need to say good luck, you will not be needing it.