Athletes have a lot of misconceptions about what it takes to gain muscle. To help clarify, here are some numbers to keep in mind in your own quest to put on muscle.
30: When it comes to protein intake, more is not necessarily better. Eating more than 30 grams of protein at one time is not effective for muscle gain and can actually lead to a significant gain in fat mass. Stick to eating 20-30 grams at each meal. This is equivalent to approximately a piece of meat the size of a deck of cards (3 ounces), 4 eggs, 1/2 cup soy nuts, or 6 thin slices of deli meat (6 ounces).
15: For most athletes, 10-15 grams of protein per snack (2-3 snacks daily) is more than appropriate. You need to limit this to assure that your overall protein intake for the day is enough without being too much. This amount is equivalent to approximately 1 cup of milk, 2 Tbsp peanut butter, 1 container Greek yogurt, or 1 string cheese.
4: It takes 3-4 weeks to see any concrete changes in muscle. So while it may be tempting to weigh yourself every day, stick to one weight per week (same day, early in the morning, same scale, same clothing) but don't do an overall assessment until at least 3-4 weeks into a training regimen.
3: Contrary to popular belief, muscle gain is not only about protein intake. In order for your muscles to absorb that protein, you need carbohydrate. In fact, plan to eat a minimum of 2.5-3x as many grams of carbohydrate as protein at each meal. So, that would mean 60-75 grams of carb for a 25 gram protein meal. An example of 60 grams is 2 pieces of whole-wheat bread, 1 Tbsp jelly, an orange, and 1 cup milk (yes - all of it).
2: If you are watching the scale, the goal is to gain 1-2 pounds per week. Anything faster is too fast, which means you may be gaining a majority of fat vs. muscle.
1: Don't arrive to training without having eaten in the 3 hours prior. Skipping a pre-workout meal even ONE time can set you back multiple days in your training regimen.