It's hard to cook when you have no idea what's in your fridge or where to find it. Fortunately, it's not difficult to keep things organized in there if you stay on top of it regularly. A quick once-a-week romp through the depths of the fridge should be enough to keep the science experiments at bay. This should take about 15 minutes. If your fridge is a total disaster, just work on it 15 minutes at a time, every day for 1 week and you should get it under control.
Remove any spoiled food and toss in compost, green cart, food disposal or (last resort!) garbage.
Found stuff that's still edible?
Make a plan to use it in the next 24 hrs (i.e. tomorrow's lunch or dinner)
Freeze it for future use (make sure to label it clearly with the date and type of food- trust me, you won't remember what it is 2 months from now when you find it at the back of the freezer!)
If you have leftover mashed potatoes, freeze it in approximately 1 cup portions (we'll talk about what to do with them later.) If there are little bits of a few different cooked vegetables lying around, you can freeze them together if they seem compatible (e.g. green beans and carrots) - they can be tossed into a soup, stew or other dish later. If you have leftovers of an entire dish (like a casserole or soup) portion it out into single servings for future use when quick lunches or dinners are needed.
If you do a once-a-week clean out faithfully, you'll always have a good idea what's in your fridge, and you'll drastically reduce the amount of food waste in your home - and the amount of money you're spending on groceries!