I'm terrible about this myself, so these days I keep a stock of frozen veggies and fruit (clean 15 or organic), and only buy fresh if it's a specific thing in our meal plan. I try to make the meal plan on Sunday (ZipList is pretty cool) using what we have in stock, and add any fresh ingredients to my list so I can grab them when I'm out. The only farmer's market worth going to this time of year is a 45 minute drive, so I go once or twice a month and stock up on meat/eggs, and try to limit the veg to what we can use quickly or won't spoil fast like butternut squash or sweet potatoes. These days, about the only fresh stuff I buy regularly is zucchini (for zoodles or sauteeing), rutabaga, onions, sweet potatoes, bananas, celery, cucumbers and carrots (for my preschooler's lunch), and heads of romaine because they don't go bad as fast as loose salad mix. If our carrots, celery, or onions are starting to look sad, I toss them in the freezer to use in stock later. I had to toss some zucchini the other day, it was a very, very sad thing.
I think a shopping routine depends a lot on what you have access to and that can vary *a lot*. Primal in northern Delaware is a big job, lol. After 6 months I am still adding to my sources and shifting where I buy what I need. DH and I have subscribed to a CSA and installed a couple of raised garden beds, so I expect come summer we will be adjusting again. If I can find a nearby source for top quality meats, trips to Costco and Whole Foods will need to be adjusted too.
Another thing that I am still getting a handle on is how the total quantity of food is shrinking as we improve the quality of what we eat. I expect to be in flux for at least another year, lol.