For a long time now, I have kept a simple notepad on the fridge. It's not a blank one, but it says each day of the week, Sunday through Saturday. Day-of-the-week notepads can normally be found at the dollar store. The weeks that I sit down and plan out a realistic menu are the weeks that I find we do well with our food spending and we don't give in to the "let's just go out to eat" thoughts.
Here is what I do. Sit down, decide what you may have in your pantry, or a recipe you've been meaning to try, or whatever your approach. You may also, if you have kids, need to look at the school lunch menu so you don't end up making something very similar for dinner the night before or the night of. Think also about the time you need to spend on each recipe/meal. Then, thinking about your schedule for the week, begin assigning meals to days of the week. If you know you have ballet on Tuesday, then make it leftovers night. If you have all afternoon Sunday to make a big meal, schedule that new recipe. Make it work for you.
Then, flip the paper over and make out your grocery list. Scan your recipes that you have planned. Is there anything from the recipes that you don't have in the pantry or fridge? Now's your chance to write it down. Look at your basic needs for groceries at the same time. Milk, bread...
Go shopping. Use the list. Stick to the list as closely as you can. I know, there's always something that catches your eye at the store. Oooh, it's shiny! Oh, it sparkles! The point is, if you need it, go ahead and get it.
This method of planning works really well for me, and with practice, it can work well for you, too! I found a website that is currently offering a "Fridge Friend" for free if you want to try this out, it even has a section to make out your grocery list on the front and a few tips on each page!
PS. The flowers above are red Verbena and are very hardy in full sun, here in the south!