Even though I'm no kind of strict Traditional Foods mama and never will be, I found several traditional foods-type books to be very, very useful for enlarging my ideas about how/what/when to eat for meals and snacks. Nourishing Traditions by Fallon is a huge hippie tome that's just fun to read, Real Food by Planck is shorter and more relevant to the typical 21st-century lifestyle.
To keep the eating in this house reasonably healthy, I:
* avoid buying chips, crackers, cookies, and any sort of food or beverage containing HFCS. I also avoid juice and soda for me and the kids, not because I think juice and soda are Always Evil, but because they add calories we don't need and cut into the amount of water we drink in a day.
*have a "snack basket" for the kids with apples, bananas and organic granola bars. In addition to raisins or strawberries or sunflower seeds or whatever else we might happen to have on hand at any given time, these are the only snack choices.
* bake cookies and bread to satisfy our yen for carbs. I am still trying eliminate the purchase of storebought bread for sandwiches, but it's hard to give up that convenience. So I buy Nature's Own, which is very reasonably priced at Costco and has no HFCS.
* serve a rotation of simple dinners - pasta, beans and rice, grilled chicken/steak, accompanied by salad or frozen veggies. I hate to cook, and I'm bad at it. So simple is what works for us. And no dessert as a regular thing.
* source my milk, eggs and meat from local farmers as much as possible. It takes a while to make the connection with the right people (good prices, convenient pickup location, flavor/texture of meat that meets family expectations), but it's soooooo worth it. I grow produce and visit the farmer's market in the summer and buy some produce locally in other seasons, but the price/quality comparison with industrial organics leads me to buy organic frozen veggies pretty often in the off-season.
My husband, who works at home, eats an exceedingly boring diet of frozen minestrone soup that I make by the crockpot-full every couple of weeks, fruit, coffee, Diet Dr. Pepper (yuck) and whatever I make for dinner. If there is a cookie or cracker in this house, he will find it and gorge himself on it. If there's not, he does fine without it.
The kids and I love fast food, and so we go through the drive-through sometimes. I've decided not to agonize about that, and just try to minimize the junk in the house.
I'd say the first big step in changing one's food lifestyle is to have a SHORTER grocery list. But the ingredients for the dinners you plan to cook that week, milk, eggs, cereal, bread, sandwich fixings and several healthy snack items such as fruit, and nothing else! You will find yourself skipping whole store aisles.
Sorry to write War and Peace here, this is a favorite topic of mine.