#9: Train your small muscles like the rotators in your shoulders, and make sure you keep your flexibility. You need your body to function as a unit to pack on more muscle. If you skip training smaller muscles, you're likely to get stuck at plateaus more often.
#8: Don't follow up your workout with cardio. I actually read the other day that you should focus on what you want most LAST in your workout. So if you want more muscle you should weight train last.
#7: Eat for Christ's sake. After your workout is done you have one task: to eat.
#6: Don't skimp on days off. If you cannot make your best performance due to fatigue you won't generate enough force and lift any decent poundage!
#5: Train when you're the most motivated. Doesn't matter that studies indicate strength peaks at 4 pm or testosterone is highest in the morning, if you're most excited about training at 6 am.
#4: Take your post workout shake and drink some of it when you start working out, or even right before. That way you never hit the low blood sugar bottom and also it might help you recover faster.
#3: If you think you may be eating too little, you most likely are. The worst thing you can do while building muscle is to under eat.
#2: Prepare your workouts. KNOW what you're about to do and write down goals for each workout. Is it to do one more rep? Another set with a certain weight? Have it all written down and then execute. I don't believe in keeping it in your mind. When you write it, you sign a contract to do it.