1. LIFT BIG - Give your muscles a reason to grow. Don't do endless sets, be intense. Go heavy, but don't remain much longer than an hour. Train 3-4 days a week. Hit failure and make that last set count.
2. EAT BIG - You must eat to grow. For gaining, take 20Cal/lb bodyweight daily. Get 30g protein per meal. Eat 6 meals a day. Don't be scared of fats. Cut junk food. You will crave chicken breasts, tuna shakes, pasta and chocolate milk.
3. SLEEP - Recovery is key. If you're an meso/endomorph, get 8-9 hours a day, an ectomorph needs at least 6-7. You grow outside the gym, not in.
4. WATER WATER EVERYWHERE - Carry that gallon jug with you at all times. Drink 8 litres a day. Keeps you well-hydrated so you can train at your best and have your caloric needs in check.
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.
6. YOU AIN'T 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.
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.
8. DON'T OVER TRAIN - 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.

Time to hit the iron.