"Buy low, sell high," is gospel when it comes to investing in the stock market. But when I'm in the market for almost everything else, I say, "Buy used, not abused."

See also: Make planning yard sales a family affair.

I'm a huge fan of shopping at both yard sales and thrift stores for everything from clothing and furniture to housewares, appliances, and office equipment, These are the cheapskate shopping venues where I find gently used items that routinely save me 50 percent or more compared to the same items purchased new.

At yard sales, you never know what you'll find, which can be a blessing and a curse. If you like to browse and search for one-of-a-kind treasures at bargain prices, shopping at yard sales should turn you on and save you money.

But if you're in the market for a specific item—say a pair of shoes in your size—you could burn up tanks of gas and time scouring yard sales and still not find what you want. For some purchases, thrift stores may be the better option.

Like regular department stores, most thrift stores carry a range of used items, including clothing, housewares, and furniture. There are more than 5,000 thrift or secondhand stores in the United States. Most of them are operated by charitable organizations such as Goodwill, Salvation Army, or other nonprofits. The following online directories can help you find thrift stores nearby:

• Thrift-Shop-Directory.com
• TheThriftShopper.com
• ResaleShopping.com

Don't be shy about shopping at thrift stores. They're not just for economically disadvantaged customers. In fact, nonprofit thrift stores need all the customers they can get, since their goal is to liquidate donated merchandise as quickly as possible in order to get the funds they need to carry out their mission-based work. You'd actually support the charity by shopping in the store.

Here are my top-10 tips for finding the true bargains at yard sales and thrift stores:

• Location, location, location. Yard sales and thrift stores in upscale neighborhoods often have higher quality, brand-name merchandise.
• At yard sales, if you snooze, you lose. Show up for yard sales as soon as they open for business—maybe even a bit earlier.Otherwise, you might miss out on some bargains.
• Shop early in the week at thrift stores for the best selection. Many people drop off donated merchandise over the weekend, and it's put out for sale at the start of the workweek.
• Haggling is in. Don't be afraid to ask for lower prices on items at yard sales or thrift stores; many times, prices are negotiable.