I keep an inventory of my pantry, fridge, and freezers. I have a little magnetic shopping list on the side of my fridge, and a weekly menu posted on the fridge. (This helps in that I don't have to answer questions or think, and also when I'm up in the morning getting breakfast ready, I can see "Oh, I need to defrost the fish" or whatever instead of waiting until I remember it). There are some things that are on a "running list", that I will buy every week because they are always being used and I always want them in my inventory (milk, tomatoes, etc).
Get out your calendar or dayplanner so you can see at a glance what each day is like. We have days that are ridiculously busy (today: 2 back to back exercise classes starting in 40 minutes, then oldest to preschool a little late, story time with youngest, LOTS of chores to finish up before weekend, clean out/wash car, donate stuff that's been outgrown, lunch/nap with youngest-that's when I'll cook, oldest goes to kung fu for an hour, then we go to an indoor playground to get some energy out AND see the pet fair they're having tonight because we're searching for a new family dog, then the evening stuff begins). On days like this, you need either leftovers or something super easy (crockpot?). I have leftover bbq pulled pork in the fridge from when we had bbq sandwiches, baked beans, and home fries. Tonight I'll serve baked potatoes stuffed with the bbq, cheese, green onions, and a little sour cream, served with steamed broccoli. The easiest thing possible (bake some potatoes, steam some broccoli, give them the condiments, the end!). On the days that aren't crazy, you can have more involved meals.
Write the days of the week, then leave space for all 3 meals and a snack if you do snacks. Breakfasts are easy for us: I'll rotate cereal/banana and yogurt over granola on weekdays. Saturdays is oatmeal, Sundays we'll have something different (pancakes; eggs, bacon, biscuits; french toast and fruit, whatever). Lunches: Pasta salads, sandwiches, leftovers. Dinners: I rotate this around so that I'll have chicken, then beef, then vegetarian, then pork, then fish. Leftovers 1-2 nights/week. If there's leftovers, but not enough for a 2nd meal for all 4 of us, that's a lunch for husband, unless it's my favorite meal of the moment. (It's usually a small lunch sized portion left over, OR enough for everyone to have another dinner).
Try to come up with meals using what you already have in your house. Then on your shopping list, write what ingredients you don't have for that meal (need more butter, or an onion, or whatever). Then see what's in the sale ads and finish up the menu or even just have it in stock for another week (meats can be divided and frozen, etc).