1. Buy fresh produce when it's in season and freeze it.
Fresh produce is always great, but the cost can add up fast. Stick with buying what's currently in season, and consider stocking up when you find a good deal.
In the summer I will buy three or four dozen ears of corn when it is two ears for a dollar (or less). You can cut it from the ear and freeze it in bags, or freeze it whole (though the former takes up less freezer space). Then you have (really great tasting) corn for cheap for several months. Same goes with other vegetables.
2. Look for sales and plan meals accordingly.
If your local grocery store offers a savings card be sure to sign up, and check the weekly circular to see what's on sale. Instead of shopping for groceries based on your weekly meal plan, consider planning your meals around what's on sale.
3- Embrace whole grains and beans.
Beans and whole grains, like quinoa, freekeh and brown rice are an inexpensive and tasty way to bulk up meals, and can even be a meal in themselves.
I use black beans to stretch my meat. You can spend $15 and get the ingredients to make chili which will last for one person, 10 meals. I mix (cooked) black beans with ground turkey and make turkey burgers using that.
4. Shop at ethnic markets.
Consider checking out local ethnic markets. Not only are you likely to find a bargain on certain products, you'll also find some really interesting ingredients.
You can buy really varied, interesting, cheap noodles in an Asian market. I never buy rice noodles in a supermarket - they're very overpriced. That goes for just about any condiments/sauces for Asian meals. Go to an Asian grocer and stock up. The produce is usually cheaper too. One of my Asian stores has really fresh fish and meat. Just know the store and ask about it.
5. Go to the farmers market at the end of the day
Depending on where you live, farmers markets may or may not save you money during regular hours. Consider visiting the market at the end of the day, when you could very likely score some great deals.