First thing is to learn as much about simple nutrition as possible.

When I was lifting heavy I lived on egg whites and a plain bagel for breakfast, met-rx shake around 11, salad and a quart of skim milk for a late lunch, can of tuna around 4 or 5, workout, dinner of steak or chicken breast no later then 7:30.

Always remember that "Carbs after 8 add weight".

Working out 4 times a week and following this diet (with one cheat day a week) I went from a 38 waist to a 31 in about 18 months. Put on about 30 pounds of muscle.

Good luck, it takes lots of discipline.