Plan ahead and spend less on food
The main hurdle to eating on the cheap is figuring out what to buy where. This may take some time as you shop around at all your nearby grocery stores. It's certainly a process of trial and error, especially if you're trying to eat healthy like I do. Avocados may cost less per fruit at your local produce market, but you may not be getting as much for your money if they're small and brown on the inside. It may be worth it to make a visit to the dreaded Whole Foods and shell out twice as much for twice the quality.
While figuring out where you can get the cheapest goods, it's helpful to keep an eye on the size of the package your food comes in. Write down how much food costs per ounce at every store near you, not just per package. Make sure you're actually getting the most food for the least money. And if any local stores offer bulk purchasing of basic goods, go for it; it'll usually be much cheaper due to the lack of packaging (I can get a pound of good, bulk salad mix at my local produce mart for the same price as five ounces of the packaged stuff).
And as hard as it may be, make sure you're cutting down on those foodstuffs that your body doesn't absolutely need--even the ones advertised as healthy. Pre-wrapped granola bars may satisfy your sugar cravings while making you feel good about their whole grain content, but it's far cheaper (and healthier) to just make your own every so often. Stay out of the corporate traps and DIY your snacks for a more budget-friendly diet.
The grocery bill may be one area where people are less willing to cut down on spending, but with some planning and a little extra work, it's absolutely doable.