1. Set solid goals.
Most people who set out to build muscle fail to do so because they failed to set solid goals. Building muscle is a science and like all scientific endeavors you need to start out by setting up your goals and think through each detail of what you need to do to attain them. One of the problems is that there is so much conflicting literature out there on the topic of muscle development, that it can get very confusing.
So how are you supposed to know which is the right training advice to take? easy they all are (generally speaking) The problem many people seem to come up against is a plateau in their muscle development, i.e "I was getting great results but now I don't see any change". The answer to this is that your body has become accustom to the training you are putting it through, try changing at this point to a different training regime. I would recommend a change every 12 weeks, with slight variations each 3-4 weeks for optimum muscle development.
2.Don't thrash it out!
I see this kind of thing all the time, guys load up the maximum weight they can handle and pump out 8-10 reps like a rabid dog...wasting your time people! You should try and control your reps in both the constriction and extension phases of the rep. I also recommend pausing at both ends of each rep to put maximum focus on the muscle and not just use that oh so wasteful moment. In short if you are throwing the weights up and just barely making 8 reps then it is too heavy, control your movements, focus on your breathing and the results will speak for themselves!
3. Rest between sets.
This will sound strange but rest periods are dependent on the intensity of the set, lets say you do higher reps around the 12-15mark, then the rest period will be shorter around 1min. Whereas when you are hitting 1-5 reps you will need longer to recover your energy. It sounds like it should be the other way around, but you actually use more energy lifting a heavy weight a few times then you do lifting a light weight over and over again. You need the rest so that you can put maximum energy into each set and get the most out of your time under the bar! Your muscles will thank you for it.
4. Stay balanced
Too often people focus so hard on building a muscle group that before they now it they are way out of balance. The most common example of this is the bench press fiend. Typically these guys have super rounded shoulders which is caused by the pectoral muscle overpowering the muscle in the back, this is going to hurt them in later years! Balance your workouts, even though it may seem that the bench press is where the real man trains, grab that seated row bar or hyper extension rack and get to it, you will look better and feel better for it!
10. Get some downtime.
The basic premise of muscle building is this; you blast a muscle by lifting weights essentially destroying the muscle, your body then uses protein to rebuild the muscle. Since the human body is a self perfecting machine, loaded with foresight it will rebuild the muscle stronger and bigger, so that next time it is faced with a similar challenge it can cope with it. If you don't give your body time to recover and rebuild properly, you are simple breaking down an already broken muscle and gaining nothing while damaging it. Take the time to rest and recover, keep your protein levels up and the results will blow you away!