Plan your weekly menu in advance and only buy what you need for the week. I have a spreadsheet divided by day/meal, then with a miscellaneous section for cleaning supplies, etc. We save at least 30-40% when using the list. Also, don’t go shopping on an empty stomach. I’m also a big proponent of store brands and manager’s specials. I’ve gotten some great deals on the manager’s rack.
Sam’s Club and other stores like it can help save money if you do your research but a lot of their prices aren’t as good as going with store brands, sales and coupons. Some stores offer better deals with their discount cards (e-coupons, etc.) so check out their websites and take advantage of what you can. Also, some higher-end stores may have good bargains. We buy a handful of items from Trader Joe’s because they have the best prices on those particular items.
Buying in bulk isn’t always the best deal. Even if it gets you a better per unit price, if it’s not something you’re going to use in a reasonably quick amount of time you could run into problems with space and spoilage. That being said, if it’s something you use a lot, don’t have to worry about spoilage and it gets you the best bargain, go for the bulk. We buy 20 lb. bags of rice and olive oil by the gallon. I’ve also noticed that a lot of stores have adjusted their prices so that the larger sizes are no longer the best bargain. I picked something up the other night (can’t recall what at the moment). We needed a good amount of it so the 128 oz (or whatever) jar would have been best but the unit price on it was like 3.4 cents per ounce. The smallest size had a unit price of like 2.8 cents per ounce, which I had to explain to my wife when I brought home 11 small jars instead of one big one.
As far as recipes go, try looking up recipes on websites that will let you adjust the recipe by number of servings. We have five kids so the 4 serving recipes are too small and the 8 serving recipes lead to too much waste. If I can adjust a recipe to give me exact amounts instead of just doubling or guessing at a recipe we tend to end up with just the right amount, or really close to it.