It comes down to a few simple things. (simple to figure out, not necessarily to follow through with :P)
You need to burn more calories than to take in and do this while feeding yourself enough of the nutrients your body needs to maintain as much muscle as possible.
Here are a few thing that should help get you started:
LV's Grocery List - WorldFitness Training Forum
Nutrition 101 - WorldFitness Training Forum
RossTraining.com • Index page
John Berardi - Post Workout Nutrition
Delaware Consumer Health Information Services
FitDay - Free Weight Loss and Diet Journal
MapMyFitness.com - Map your Running Routes. Find Runs. Join our Community of Running. Runner Social Network. Calculate Calories, Online Pedometer, Distance, iPhone, and More.