Wow, so much good info here! Allow me to add some tips from my own life.
If you regularly get the Sunday paper, clip all the coupons. If it's something you just don't use or won't use, stick the coupon next to the item on the shelf for someone else. If it's an item you would use/eat if the price is right, keep it. You can use coupons on marked down items. I once got enough cereal for an entire month for less than $10 (6 large boxes, so prob more than a month). If you don't usually buy the Sunday paper, you can usually find a website that tells you what coupons will be in that weeks paper, plus the deals in the store flyers. I'm in Georgia, so I've found that the Southern Savers website has all this info.
Find out when you're favorite store marks down items. Some do meats twice a week. I like to hit my local to work store right after they open, mostly bc it's right as I get off with. They usually have a cart or two of marked down items, often seasonal, right up front. I've gotten several items as a steal, such as rice, beans, popcorn, even diapers once that I got for one of my daughter's friends. Those diapers don't go bad, and they can always be donated to a food pantry or pregnancy center.
Check out cookbooks from your local library. It's a great, free way to find new ways of making meals with the same old ingredients. Also be on the lookout at yard sales and thrift stores for older cookbooks, like from the 50s and 70s. I use these decades because people were being more frugal due to financial times they were living in.
Another place to get cookbooks and other things at potential great prices is ThriftBooks. I've gotten several things from them and have always been pleased. Honestly, though, I usually buy DVDs from them, but if you find a great cookbook at the library, you can check at TB for it. You can even put it on your wish list and they'll send you an email when it comes in. One of the best things for me about TB is that they are not owned by Amazon.
Get together with a few friends every couple of months for a big batch cooking freezer meal day. I absolutely love the Don't Panic! Dinner's In The Freezer books (there are 2 that I know of). This book gives you the recipes, how to multiply it, plus all the instructions for how to store, cook, and serve the meal. You can come together in one day and make several meals to put in your freezer, plus there's the added benefit of a great social time with your friends.
Pinterest is a great place to find recipes as well.
I'm about to go back on a health related eating plan, and I'm grateful the doctor who wrote it and the books that go with it gives sample menus and a day to day schedule for the first week so you get an idea of what to do when. I was on this plan a few years ago and it was wonderful for me. And then I had some sugar and well....
When you have an abundance of eggs (after a huge sale, find a great markdown, or if you have chickens), it's a great time to make up things like cookie dough or quiche for your freezer. Before my last bit of depression, I used to bake dozens of cookies at Christmas. I would buy up baking supplies at Easter (except for eggs) and then in the summer when everyone I know had eggs coming out of their ears, I made cookie dough. You can either package the dough in bulk, like in plastic bags, or individually for drop cookies. If you do the individuals, you can just thaw and bake a few when you need a pick me up.
Use up all of that chicken! Say you roasted a chicken, or bought one of those rotisserie ones. Don't toss the bones! Make chicken broth/ stock! Toss the bones, skin, whatever you didn't eat into your crockpot along with onion tops, bits of celery, carrots, whatever extra pieces of veges you tossed in the freezer, cover with water, and add a tablespoon of vinegar. Turn that puppy on low and let it go for 12-24 hours. Skim off the foam and dip out the broth into a pitcher or bowl to cool before putting it in the freezer (I usually double bag in quart zip lock bags, they freeze flat and are easier to store). But wait! You aren't done yet! Cover it with more cold water and repeat! You can keep doing this until the bones turn to mush, that's how you know you've gotten all the good stuff out. Then you can add the mush to your pet's food as a treat, if they like that sort of thing. I've managed to go about 5 days doing this daily, about 8 gallons. Which I needed, because I was using a lot of broth on that plan I mentioned earlier.
Get together with someone to go a couple of times to a big store to stock up. It will save on gas. I've got a friend who arranges a big trip a couple of times a year to a huge farmers market in the Big City about an hour away from us. They carry a lot of bulk spices and tea, plus they have a lot of specialty things we don't have where we are. We plan to go on a week day, everyone riding along usually gives $5-10 towards her gas (she's got a really big vehicle with lots of trunk space), and we plan to stop somewhere for lunch on the way back. The lunch is a bit of a splurge, but it's great fellowship and a chance to try something new. We usually try to go in October to avoid all the chaos of holiday shoppers.
Make friends with your local farmers. Often you can arrange for deals on trades or buying in larger quantities. I've traded knowledge and crafted items for food, sometimes without knowing I was doing it. One of my friends asked me to teach her to knit. I went over and spent 2 hours with her trying to get her comfortable with the one stitch. I'd also taken her some things I'd accumulatedthat she liked (buckets, actually), but she sent me home with a huge flat of her organic produce - blueberries, blackberries, onions, squash, cucumbers!
For storage in bulk of dry items, get food grade buckets. But before you go out and buy them, check with your local bakeries, grocery stores, donut places. I work for a Dunkin franchise, and they usually throw away the buckets the frosting and glaze come in. I've been bringing them home and selling for $1 each. It's cheaper than buying buckets at Home Depot, plus they are already certified food grade and have rubber gaskets in the lids.