Here's some tips that I follow:
I keep a pantry, stocked up with the basics (I think the "basics" can also be slightly different for each family). For us, that means I always have : flour, butter, milk, eggs, rice (brown, white and basmati), pastas, dried beans, canned chickpeas, baked beans, spices & seasonings, sauces. I also keep my freezer stocked with basics: frozen peas & carrots, frozen corn, frozen edamame, frozen fries, homemade beef & chicken stocks, three or four different cheeses.... you get the picture! I am ALWAYS trying to get coupons for these basics and I try to stock up on these items (they usually don't go bad quickly) when I can get them on good sales.
From there, I scour the Thursday papers (in our area, the grocery flyers are out on Thursdays) and see what's on sale. I'll compare sales items against any coupons I have. The sales & coupons will usually determine what I buy and what I make for the week. I will write up a quick list of 5 dinners and 4 lunches that I will prep for the week, and then it's out to shop.
From late May to November, we shop local for produce and meats, so I sometimes call ahead to our local greengrocer's and my butcher to see if anything is going to be on sale. Our greengrocer's has a fantastic website that shows what produce is in season at what time, so that provides quite a bit of inspiration. Right now, it's good-eatin' time. Peas are done, but green beans, zucchini, lettuces, cauliflower, sweet potatoes, new baby potatoes, tomatoes, sweet corn, peaches, red & black currants, ever-bearing strawberries, raspberries & blueberries are all being harvested locally. If you get to the local farmer's market at the very end of market day, the food is usually on terrific sale - you can pick up a basket of peaches for $2 instead of $5, for example.
I always try to shop once a week, on the same day. I like a routine and I find I can keep better track of what food is coming into my house that way.
Once the food is home, I try to wash up any produce and prep as much of it as possible right away. Local produce is usually fresher, but also usually much much dirtier

. So I put aside about 30 minutes to wash up veggies & fruits, put stuff away into my tupperware, portion things up (cuts of meat especially), and it's a good time to freeze up any fruit & veg that didn't get eaten in the first week, for smoothies or soups.
There are also a few good websites about making your grocery dollar go further - one blogger made a bet to eat on $1 a day. (And he managed to do it too!!).
I applaud your efforts - I noticed about two years ago that food prices seemed to go crazy, and while it does take more organizing (making a list and pre-planning a few meals), the end results are worth it.