If your shopping trips occur on a scale as massive as the Normandy Invasion, then they should be organized with similar precision. That means planning the week's meals and making a detailed shopping list based on the needed ingredients.
Supermarkets are designed to make us stray from our lists, but sticking to them helps avoid those impulse buys that often end up at the back of the fridge, shriveled or rotten. When we go to a supermarket or grocery store without a list (or hungry), we tend to buy more food than we can possibly eat.
Another idea is to find two or three recipes that use the same item so you don't end up with a tube of anchovy paste sitting in your fridge for years. There are numerous web sites like Super Cook that spit out recipes based on the ingredients you enter.
If you don't mind going to the store--or even enjoy it--smaller, more frequent shopping runs may be your best bet. That way, you'll just buy what you need for one or two nights, which reduces the odds of buying too much. It also allows you to be impulsive while minimizing waste. For more tips visit my website, American Wasteland.