Be sure to decrease your calories slowly after your bulk, adjusting them by 300-500 a day for 1 week at a time. Monitor your weight, and increase your activity level. If you diet too drastically you will lose a good deal of your gains if the muscle is not mature yet. Everyone is different in this regard, but this has what has worked for me. It takes a lot of tweaking and learning what works for you personally to gain mass and stay lean while doing it, then keeping it is a whole other process.