WITH a little practice, anyone can find good deals at a thrift shop. Here are some hints:

Look at everything. Thrift shopping is really thrift hunting. To get the most out of it you have to pore through racks and racks of clothes, boxes and boxes of shoes and stacks and stacks of books. If you give up after thumbing through a dozen green, polyster leisure suits you may miss the camel's hair sport coat. You probably weren't looking for the sport coat anyway, though, since you can't approach thrift shopping the way you would grocery shopping. Go with an open mind, not a list.

Don't buy something unless you really, really want it and it fits you. Since prices at thrift shops can be incredibly low, it's tempting to buy anything that tickles your fancy. I used to do this and subsequently spent a lot of time renting used clothes. I would see a suit that was sort of cool and buy it, whether it fit me or not. After a while I had a whole collection of very stylish suits that were designed for men about four feet tall and 50 inches around the waist and which I could never wear. Some clothes are worth buying if you're handy with a needle and thread or know a tailor who is good at alterations. Similarly, if you're the type who likes to tinker, go ahead and buy that $3 clock radio that doesn't work.

Ignore all size labels. Many articles of clothing are given away because they shrank or never really fit in the first place. That means that the size 10 sweater that you're holding up may be closer to a size 6. Most thrift shops have fitting rooms; use them.

Learn about dirt. There are two types of dirt found on thrift shop clothing: ordinary, removable dirt and permanent, everlasting dirt. While most thrift shops won't accept truly stained clothing, some does slip through. It's all right to buy something that one wash will rejuvenate, but it makes no sense to buy something stained with ingrained dirt. Be especially vigilant about armpit sweat stains and seat stains that came from sitting on something.

Keep looking. If you find an article of clothing you really like and that fits you well, look around -- there are probably more. No one comes in to a thrift shop to donate just one coat or one pair of pants, they donate in bundles. That means if you find a cashmere sweater that is exactly your size, it's a good bet something that shared its closet is nearby. My wife, Ruth, bought me three thrift shop suits that were all a little short in the arms, a little long in the legs and a little tight around the waist, but all within the realm of a good tailor. It was obvious the same man had come in and donated his outdated suit collection. (A few months later Ruth brought home a three-piece Brooks Brothers suit. You guessed it: too short in the arms, too long in the legs, too tight at the waist.)

Watch out for things in boxes. Clothes aren't the only good deals that can be found at thrift shops. Appliances, board games, books and other items are also donated. However, if it comes in a box or some other type of packaging, always open it and make sure that what you're buying is complete or, indeed, what it's purported to be. I collect Partridge Family records (a strange affliction, yes). I once bought a copy of "Sound Magazine," their 1972 opus that contained the hit "Echo Valley 26809," only to discover when I got home that what I had actually purchased was the album jacket. The record inside was a symphony by Debussy. (Some Debussy fan somewhere must have been as surprised as I was.)

Know the difference between a thrift shop and a consignment shop. Thrift shops are usually run by charitable organizations that sell donated items. Consignment shops sell things on consignment. That means you bring something in, put a price on it, and when it is sold you give a cut to the store. Prices at consignment shops are noticeably higher than those at thrift shops, but the quality is generally higher as well. For example, I paid $10 for a raincoat at a consignment shop. I never would have paid that much at a thrift store but I probably wouldn't have found one as nice.

Be realistic. There are some things you won't find at a thrift shop no matter how long you look: an original Picasso; a complete set of Waterford crystal; an inscribed, first- edition Ulysses; completely functional musical instruments; a Giorgio Armani suit. However, if you're persistent, you will find: interesting cocktail shakers; work clothes; old National Geographics; tennis rackets; Raymond Chandler paperbacks; wild clothes to wear to parties; items to decorate a dorm room; Partridge Family records.

Give and you shall receive. The thrift shop gods are kindest to those who also donate to thrift shops. When you have some old clothes, appliances, cutlery, books or furniture, return them to the thrift shop food chain for someone else to catch.