Muscle gain is about consistency with your meal plan, your training regimen, and high volume. Yes high volume. I've always trained with high volume and its always worked well for me. Typically for larger muscle groups like chest/back/legs I usually stay around 25 sets and even up to 35 for legs. For smaller muscle groups like Biceps/Triceps,Delts/Traps I stay within 15-20 sets.
Chest: I always start with a heavier pressing movement while my chest is fresh. I alternate between the flat bench and incline bench each week. Week 1 I will start with flat bench first and then do incline second. Week 2 I will do just the opposite. From there I usually go to a fly movement ( my favorite being the incline dumbbell fly). On the incline fly its important to get a great stretch across the upper chest and to get a great squeeze at the top. Never lock your elbows on these, but keep them slightly bent. By doing this it will allow you to get a greater stretch and contraction at the top. From there I will go to a decline press or weighted dips. I usually use the decline hammer strength press or a decline barbell press. From there I will finish off my chest with another fly movement (usually a pec deck or cable crossover). So as you can see I like lots of variety. When trying to build muscle you need to hit every muscle group from different angles to force as much nutrient rich blood in as possible. Typically for these chest exercises I will do 4 sets of 8-12 reps per set. I do like to utilize different training methods such as drop sets, 2-2-2 tempo, and FST 7 which is 7 sets of 10-12 reps for the last exercise of your routine. The FST 7 gives a great pump. You keep the weight the same for all 7 sets and only take 30-45 seconds rest in between sets.