What goes around comes around. There's nothing new under the sun. Yup, that can apply to clichés, and it can also apply to the world of fashion. Eventually, what was popular when you were a kid and looked silly for the next decade or three will come back into style. As a garage sale shopper and a thrifty wardrobe-assembler, you can take advantage of this cycle by following the fashion trends closely enough to know what's coming back -- and then buy it up at sales when it becomes stylish once more.
Dresses are always in fashion in one form or another. Even if the style of dress you find isn't exactly what's in right now, you can re-sew parts on or off to make it so. Of all the clothing items, dresses are one of the most difficult to make from scratch, so even if you just use the old dresses as templates, you're better off than starting off on your own. Plus, old-style dresses can be considered very classy, if dressed up with a few modern touches, so don't automatically turn your nose up at what your grandmother wore.
Patterns and colors often swing in and out of style so quickly that it's tough to remember when they weren't popular. Buy up shirts of unusual colors and patterns (if they're super cheap), and during the years they're hip again, you can pull them out of the closet and act like you just decked yourself out from a high-end store. Obviously, there are some fashions that were over the top then and are still over the top now, and you may not want to "invest" in those; but as for the rest of it, someone's gotta set the trends, and maybe you can be the one to do it!
Accessories can always be in style. Belts, necklaces, hats, and other jewelry, when paired with the right outfits, can be create a great throwback look that will instantly be fashionable. (Fashion is interesting like that. If you're intentionally being old-school, it looks good, but if it's accidental, you're "stuck in the [decade]".) If you buy accessories, you can be certain of finding an outfit they'll go with at some point, and since they can be very expensive at all other venues, it's a good idea to take advantage of the discounted prices garage sales provide.
Garage sales are awesome, right? They're like a blast from the past or a peek into the future (especially when it comes to fashion). If you love garage sales as much as we do, you should come visit us at GarageSaleCow.com and browse all the great free resources we have for people just like you