If you want to build muscle fast there are a few very important factors you need to be aware of. First of all, if you have less than Herculean genetics you need to be sure to avoid overtraining. There are several different ways to do this which are listed below.
Don't do more than 12-15 sets per workout.
Don't train for longer than an hour.
Don't train more than four days per week; three days is even better.
Don't train for more than 8-12 weeks without taking a week off.
Don't train with 90% or above your one rep max for more than three weeks in a row.
Productive mass building workouts are centered on one concept and one concept only; progressive overload. You have to consistently get stronger and lift more weight and do more reps if you ever want to get bigger. Doing the same thing repeatedly will get you absolutely nowhere and is a complete waste of your time.
Also, you need to be sure that you are using big, compound exercises like squats, deadlifts and chin ups with heavy weights. Don't waste your time with isolation exercises and pumping techniques that do nothing to help you build muscle fast.
Next, you need to be sure your diet is in order. This means that you are eating copious amounts of food every 2-3 hours. Going longer than this without a meal will impede your progress and you will never get huge. You should be focusing on organic whole foods such as grains, fruits, vegetables, nuts and seeds for the majority of your calories. The rest of your intake should be made up of clean sources of protein like eggs and fish.
Another thing that will help you build muscle fast is paying the utmost attention to your recovery. You should be getting as much rest as possible which includes sleeping a minimum of eight hours per night and hopefully even taking a short nap during the day. Another thing that can boost your recovery ability is regular massage. This can be a real massage from a masseuse or just a simple self massage with a foam roller or tennis ball. Either way you do it will help tremendously, just be sure to do it.
Although most people overlook its importance, stretching is another crucially important component of a good muscle building program. Stretching can help tight muscles grow more efficiently and can even help prevent injuries in certain instances. If you don't do any stretching now, I highly recommend that you start. You will be pleasantly surprised by the results, I'm sure.
If you follow the tips above you will build muscle fast; perhaps faster than you ever imagined. I have provided the information, now it's up to you to use it.