Drink lot's of water as mentioned already. It helps flush your system out so that your body can perform optimally. You can actually die from drinking too much water (You shouldn't have to worry about this though because the chances of you drinking that much are slim)
Eat nothing but CLEAN food. By clean I mean natural, no extra spices/condiments. If you're working out an hour or two a day, you could actually intake 4000+ calories and still lose weight from eating clean (I speak from experience).
Eat every 3 or 4 hours a day (Aim for about 5 meals a day) This helps keep your metabolism active and will increase it if it's poor.
Take a good multivitamin (I use Controlled Labs Orange Triad, but my goals are a little different than just losing weight)
EXERCISE!!! Run, Jog, Swim, Lift Weights!!
I highly recommend going to bodybuilding.com and picking off a meal/exercise plan. They have a vast amount of information on there and you should have no problem finding something that you will easily be able to work into your current lifestyle. Let's face it though, coming to a video games forum is like going to McDonalds for Vitamins...not the best choice
If you're looking for someone to follow in terms of meal/exercise I suggest Ryan Hughes, it's who I started with and still follow today.
Good Luck!