Step 1:
Train hard. Before you can gain muscle, you have to give your muscles the stimulation to grow. What this means is that you must train with weight resistance. For a good beginners program Mark Rippetoe's Starting Strength is a great resource. Practice exercises that work lots of big muscles, for instance, bench press, squat and deadlift; train at a moderately heavy intensity (5-10 repetitions per set); and train for many sets. Don't train to often, and your body will be properly stimulated for muscle growth.
Step 2:
Consume plenty of quality meat at each meal. Protein is what your muscles are made of, and after you've trained them hard, they'll need a lot of it. To gain muscle on any diet, it is highly recommended that you consume plenty of quality meat, at least three times per day. Throughout the course of the day, the athlete should consume between one to two grams of protein for every pound of body weight. The more protein the athlete consumes, the more muscle he will gain.
Step 3:
Use fish oil supplements to improve recovery and increase calories. In addition to protein, the body also needs calories to fuel the muscle building process. Fish oil is a potent anti-inflammatory, and will help reduce muscle soreness, and thus help improve recovery from training.The extra calories will also be of great benefit. Liquid fish oil tends to be the easiest for consuming larger doses. One tablespoon immediately following breakfast, and one immediately following dinner should give 30 grams of fish oil per day. If on the move a lot, then fish oil capsules can be used instead of a dose of five capsules for each major meal.
Step 4:
Keep a high calorie snack nearby. In addition to consuming food regularly, keeping high calorie snacks nearby will help prevent hunger, and make building muscle mass easier. Some nuts and dried fruit mixed together work well. If you want an extra dose of calories, you can put them in a jar, and poor coconut oil over them and let the coconut oil cool. You can then eat the snack with a spoon for a caloric dense snack.
Step 5:
Get plenty of quality sleep. Without sleep, the body cannot recover. If the body can't recover, it can't grow. Be sure to get at least eight hours of sleep in a pitch black room every night. If you want to go that extra mile, take a 20 to 45 minute nap immediately following your post-workout meal.