Stay natural? If you don't know what creatine is, why comment? Creatine will help build muscle with a good diet and weight routine.
I took it for a while. It made me gain 5 pounds but it dehydrates you. I don't now how well it helps build muscle. If I were you I would grill slices of chicken and keep them in your fridge for extra protein and amino acids. Also make some hard boiled eggs. Eat just the whites if you are concerned about too much fat. These are smart and inexpensive ways to keep your money and build muscle.