If you've never stood in the middle of a grocery store aisle desperately trying to remember what, exactly, you intended to buy, never returned from a warehouse store with 24 rolls of paper towels only to discover a stash of 10 on the shelves in the garage, and never found yourself at a hardware store unsure of which of the dozens of kinds of screws you need to complete the project you've started at home--well, you've got a thing or two to teach me!

If you're like most of us, though, your shopping routines could benefit from a few simple organizing tweaks. The following tips are aimed at helping you save time, money, and frustration regardless of what you're in the market for.

Tip #1: Know before you go
Buying things you don't need, that won't do what you need them to do, or that will be more trouble than they're worth is a surefire way to make shopping (and its aftermath) a frustrating experience. If you've ever stood before a wall of vacuum cleaner bags and tried to remember which size your machine takes, you know what I mean.

Save yourself the time, the stress, and the cash by knowing what you need before you shop. Often, this involves making a list (see below for more details); it can also involve taking measurements; writing down the name, size, or part number of a product; and doing an inventory of what you already have on hand. Armed with this info, you'll be prepared to make smart, worthwhile purchases.

Tip #2: Make a list
Even if your memory is good, chances are you'll forget at least something you need if you arrive in a store without a list. Plus, why tax your brain? Making a list takes relatively little time and effort, and it can save you a good deal of both in the end.

For shopping you do regularly (think groceries), keep a running list in a convenient spot, such as on the front of your fridge or tacked to the inside of a cabinet door. When you run out of something, jot it down. If you buy many of the same things on a regular basis, you might consider making a master list, which you can photocopy weekly (or however often you need it); throughout the week, check off the things you need, then take the list to the store with you when you're ready to shop.

For less frequent shopping, make sure your list includes the details you gleaned by following Tip #1 above (part numbers, amounts, measurements, etc.).

Tip #3: Shop smart
We all know that grocery shopping on an empty stomach (or, worse yet, with hungry kids in tow) very often means coming home with stuff we didn't actually want or need. The same holds true for other kinds of shopping: for example, it's a bad idea to shop for clothes if you've just had an "I-have-nothing-to-wear!" day, as you'll be more likely to buy things you may already have (and that might be lurking in the laundry basket) or that you won't like once you get them home.

Before you shop, have a snack, take a realistic look at your closet, think twice about the long-term usefulness of the fancy tool you've had your eye on--in short, do whatever it is you need to do to help ensure that what you plunk down cash for is what you actually need. Also consider setting a time limit for yourself in each store so you'll stay focused and will be less likely to heed the siren song of unnecessary stuff.

Tip #4: Practice one in, one out
Finally, once you get your loot home, practice One In, One Out: for every item you bring in, get rid of one item you already have. If you've shopped for groceries, you may already have done this beforehand: emptying a jar of mayo and buying a replacement at the store is an example of One In, One Out (or One Out, One In), as is tossing a wilted head of lettuce before you bring a new one home.

For other items, thinking of new stuff as replacements for--rather than additions to--what you already have can help keep clutter at bay. If you've bought a new pair of black pants, for example, put an old pair in your Giveaways bag. This will also help keep you aware of what you have, what you need, and, moreover, what you don't need.

Put these four tips to use the next time you head out to the store. You'll save time, money, and frustration, and may even begin to enjoy shopping.