Here are some tips to start building muscle today.
Pump Up With Protein
Because muscle fibers are made up of many different proteins, protein is the #1 necessary ingredient to build muscle.
One study found participants who ate 20 grams protein every 3 hours significantly increased muscle building potential, compared with those who ate 40 g every 6 hours.  So, eating good amounts of protein throughout the day feeds muscles and keeps them raring to go.
The ideal daily protein intake is about 1 g protein per pound body weight.  So, a 200-pound man should eat about 200 g protein a day. Of course, this differs depending on individual needs.
The best high protein foods to eat are chicken, turkey, fish, lean beef, eggs, beans, nuts, milk, and cheese. 
Many bodybuilders also use protein supplements, which provide a heavy dose of pure protein. Whey protein powder is generally the best choice because it has high protein content and lots of muscle-building branched chain amino acids. 
Be careful, though. Protein shouldn’t make up more than 30% of your caloric intake. Too much protein increases risk of kidney problems, dehydration, and other issues. 
Be Choosey About Carbs
Carbohydrates are used for quick and immediate energy sources, and of course, you’re going to need lots of energy while you work out. More muscle carbohydrate stores allow you to perform better during high intensity exercise, while too few carbs may lead to fatigue and lack of motivation.  Plus, if you have sufficient carbs, your body can use more protein for muscle growth and repair rather than for energy. 
Eat carbs before your workout so they can be used for fuel. Right after your workout, consume a mix of simple carbs (fruits, vegetables, and milk products) and complex carbs (legumes, starchy vegetables, and whole grains) to replace energy stores and prevent muscle breakdown.
For hard training athletes, experts recommend about 0.5 to 0.7 g carbs per pound body weight, so if you weigh 200 lbs., you’d need about 120 g carbs after your workout. 
As you choose carbs, make sure you focus mainly on fruits, vegetables, and whole grains, rather than refined sugars (these should make up 20% or less of your carb intake).  About half of your daily calories should come from carbs. 
Capitalize on Compound Movements
If you want to pack on muscle, obviously you need to put in time at the gym. To make weight training the most meaningful, focus on compound movements that allow you to use maximal weight and train many muscle groups at the same time. 
The bench press is a good choice because it works much of the upper body, including the pectoralis major, anterior deltoids, and coracobrachialis. It also works tonic muscles, including the core.
Squats work thighs, hips, and buttocks, but the primary muscles worked are the gluteus maximus, quadriceps, and hamstrings.
Dead-lifts are also a good choice because they work muscles throughout the torso, back, legs, hips, and forearms.
If you’re just getting started weight training, you may want to meet with a personal trainer: he or she can train you to do each exercise correctly, so you can get all the muscle-building benefits while minimizing risk of injury.
Start Some Supplements
There is a wide market of supplements to help both beginner and expert bodybuilder.
Many bodybuilders choose to supplement with creatine, an organic acid that supplies energy to cells. Creatine has shown to significantly improve fat free body mass, sprint performance, and lifting volume.  It also does so safely; the only side effects reported have been stomach pain, nausea, diarrhea, and muscle cramping.
Creatine is often loaded with 20 g per day for 5 days, with a maintenance dose of 2 or more g; or loaded for 9 g per day for 6 days with a maintenance dose of 3 g per day. 
Effective pre-workout supplements often contain muscle-building amino acids as well. Branched-chain amino acids like leucine, isoleucine, and valine make up 35% of muscle mass and are essential for building cells and repairing tissue. They also help the body synthesize other amino acids needed for muscle action. 
Better still, certain amino acids like arginine, histidine, and lysine stimulate the release of growth hormone, which aids muscle growth and lean body mass. 
As you choose supplements, make sure not to buy brands containing dangerous stimulants: for example, DMAA, yohimbe, or more than 500 mg caffeine. These stimulants may briefly improve performance, but also increase chance of heart attack and stroke.
The best supplements contain ingredients proven to work in studies and are backed by positive customer reviews.
About the Author
Jake Gates is a freelance writer for http://www.BestCreatine.org, in the field of health and fitness. He specializes in healthy living and nutrition. Jake is passionate about contributing to his community. Jake currently resides in Salt Lake City.
 Moore DR et al. “Daytime pattern of post-exercise protein intake affects whole-body protein turnover in resistance-trained males.” Nutr Metab. 2012; 9 (1): 91. Available from: http://www.ncbi.nlm.nih.gov/pubmed/23067428
 “How Much Protein Per Day To Build Muscle, Lose Fat & Be Healthy?” Available from: http://www.acaloriecounter.com/diet/how-much-protein-per-day/
 Will Brink. “The Whey It Is: The Truth About Whey Protein!” Available from: http://www.bodybuilding.com/fun/willbrink3.htm
 Miriam E. Nelse. “Will Eating More Protein Help Your Body Gain Muscle Faster?” Available from: http://www.webmd.com/fitness-exercise/news/20020529/will-eating-more-protein-help-your-body-gain-muscle-faster
 Ben Greenfield. “Should You Eat Carbohydrates Before Exercise?” Available from: http://www.quickanddirtytips.com/health-fitness/exercise/should-you-eat-carbohydrates-exercise
 “Carbohydrates Are NOT The Devil!” Available from: http://www.bodybuilding.com/fun/planet30.htm
 Shereen Jegtvig. “How Many Carbohydrates Do I Need Each Day?” Available from: http://nutrition.about.com/od/askyournutritionist/f/howmanycarbs.htm
 John Berardi. “Lean Sexy Hard: Weight Training for Women.” Available from: http://www.bodybuilding.com/fun/berardi12.htm
 Richard B. Kreider et al. “Effects of creatine supplementation on body composition, strength, and sprint performance.” Medicine & Science in Sports & Exercise. 1998; 30 (1): 73-82. Available from: http://chua2.fiu.edu/faculty/kalmand/HUN6248/ppp/MSSE%20Efx%20of%20creatine%20on%20body%20comp%20strength%20and%20sprint%20perform%20CLASSIC%20Kreider%20-Almada%201998.pdf
 “Creatine.” WebMD.com. Available from: http://www.webmd.com/vitamins-supplements/ingredientmono-873-creatine.aspx?activeIngredientId=873&activeIngredientName=creatine&source=1
 David Galanis. “BCAA’s: The Building Blocks of Muscle.” Available from: http://www.bodybuilding.com/fun/bcaa.htm
 Richard B. Kreider. “Effects of Protein and Amino-Acid Supplementation on Athletic Performance.” Available from: http://sportsci.org/jour/9901/rbk.html