I like OR's advice, but in keeping with the spirit of it all, here is the complete (but still somewhat abridged) version.
Almost all of us instinctively know what we should and shouldn't eat. Some things get muddled by what we are told by the media and other entities, but when it comes down to it, high quality meat, cheese, vegetables, seeds, nuts, roots, fruits, and even grains are pretty decent for you. Depending on your goals and personal metabolism, certain things may work better for you.
It should be clear to anyone that heavily processed meats (hot dogs, bologna, etc), processed cheese food (think velveta or American Cheese singles), sugars, highly refined grains and their products, are a bad idea. This doesn't mean you can never have them again, but limit them severely. There is no reason at all to continue drinking sugared drinks, eating pizza roles, and dipping corn chips in velveta & rotel cheese sauce. Damn that sounds good. But if you want to lose fat, stop eating like that.
Base your diet around good food. Eat real foods that have only 1 ingredient on them. Buy fresh meats, veggies, and the like. Learn to cook. Cooking is a joy once you get good at it. Stop eating at restaurants. If you cook every meal at home, and cook it from fresh ingredients, your health will improve. This is true even if you have bacon and eggs 5 times a week, hamburgers, spaghetti, even more decadent things like Chicken Picatta or Pork Chops in a dijon cream sauce.
Track your intake and figure out how many calories you are taking in. You should be eating until you are satisfied, but not painfully full. This is tricky for me personally, as satisfied is usually 3 burritos past where it becomes difficult to breath. Yet following the above advice, I dropped 145 pounds in a year. As your weight loss slows, adjust your intake and exertion to keep up with the demands of your body.
Don't rush to lose the last 5-10 pounds, as you will need to begin to transition into a maintenance mode. Let them come off slowly, a pound every week or two. This will help prevent the bounce-back that a lot of crash dieters experience.
Above all, don't go back to your old habits. Nothing good can come of that. Enjoy your new health, and live life to an extent never before possible.