Learn to cook your own food. Don't worry about buying the highest quality foods, such as vegetables, so long as they're decent to good quality. If you can cook properly, with seasoning and whatnot, you can add your own flavors and textures to food/meals that will distract you from the fact that you aren't actually eating a $40.00 steak, or something like that. Also, don't be afraid to drink water. It's better for you anyway, and it's free. Buy less drinks, and save your beverage money for beer and the likes. Drink water at meals, aside from a little milk in your fridge for cereal or for cooking etc.
That's what I'd do. Cooking is how you're going to save your money. Also, if you're creative with your cooking, you can eat good meals for little to no money. Try buying a bunch of KD, but add seasoning and flavors to it, as well as actual cheddar cheese. That's a great way to make a real tasty dish of pasta, for like 3 bucks. There's so much you can do with a little creative modification.