Also do not workout over 45 minutes. Due to the stress hormone which is called cortisol, at this point it will eat muscle tissue and increase body fat. The best results to get natural muscle gain workout about 30 minutes a day. Did you know eating the wrong foods can make you loose muscle mass? Yea crazy right so be careful about eating certain foods.
When you workout in the gym be quick so your muscles can start the recovery process. Do not over work your muscles, that's rule number one because you will not receive any muscle growth by doing that. Your body can only take so much each day in-order to see results. So give the body time to rest by doing this, it also helps the muscle to heal so they can get bigger and stronger. It will be very difficult to gain muscle if you do not let your muscles heal, and im sure you wouldn't want to make things difficult for yourself.