You hardly need us to tell you that vintage timepieces are, well, timeless: fashion accessories that double as one-of-a-kind homages to the aesthetic sensibilities of generations past, and wearable, functional pieces of history that have miraculously stood the test of, fittingly enough, time.

It’s no wonder, then, that antique watches are all the rage, with collectors and consumers alike scooping up every Patek, Rolex, and Omega they can find. But in such a booming market, there’s plenty of room for error, either at the fault of an uninformed buyer, or an unscrupulous vendor. Here are a few tips that could make all the difference between ending up with an heirloom masterpiece, or a useless hunk of metal.

Follow Your Heart

With innumerable options spanning the last century of modern watchmaking, it’s easy for a watch hunter to feel overwhelmed fairly quickly, whether they’re trolling the internet, or hitting up established dealers. Sometimes, this results in settling for a “decent-enough” watch that you’re only lukewarm on. Don’t rush the process. Wait for the one that speaks to you. You’ll know it when you see it.

Service is Everything

This should go without saying, but you get what you pay for. Often, the value of a vintage watch is partially determined by how well it’s been taken care of. Has it been serviced regularly with the manufacturer? Does the watch have paperwork to back that up? The original box, receipts, and informational materials? If the answers are yes, you’ll ensure that your new/old timepiece lasts long enough keep ticking for a lifetime, and will have it backed up by a pedigree, to boot.

Beware the Franken-watch

A lot of professionals contest that a watch’s value lies mostly in its dial. Is the dial original to the watch, or has it been replaced over the years to come across as more aesthetically pleasing? Same goes for the parts. Have certain elements of the mechanism been replaced over time? Proper documentation can provide the answers, but caveat emptor, everyone—a watch that has been cobbled together out of pieces of other watches is going to give out more quickly, and frankly, won’t have the charm a vintage watch aficionado is looking for in the first place. There’s always even the chance that a certified servicing professional won’t even touch a watch unless all the parts are original, or have been replaced with the appropriate parts. (Suddenly a $500 service turns into a $5,000 service. Ouch.) Speaking of which…

Don’t Fear the Patina

A lot of vintage watches have a patina—an aged appearance on the dial—which is just fine (or preferable) if you’re in the “it adds character” camp. But for our purposes, let’s expand the definition to the overall wear of the watch. If the watch has some dings and nicks on it, but is otherwise mechanically sound, keep it on the top of your list. There are a lot of folks devoted to the idea that excessive polishing of the face and case (included with regular servicing) actually dulls the watch’s appearance in the long run. Part of the allure of a vintage watch is that it still carries its battle scars, so let them shine. (If anyone knows where we can get a ‘60s Submariner that’s never seen a polish, let us know.)

Treat It Well

Your watch is new to you, right? Waterproof means waterproof? Not quite. It’s always best to keep in mind that this watch, despite regular servicing, is no spring chicken (especially of you’re wearing a pre-‘70s model). As we said, a watch that contains its original parts is ideal, but these parts do wear a little over time. In short, take it off when you swim or shower, and maximize its lifespan.

Have Some Fun

A little while back, we talked about watch straps, and there’s hardly a more well-suited candidate for a nifty strap than an older dress watch. If your style says, “I’m putting a canvas strap in my college colors on this fancy ’68 Tag Heuer,” then make it so.

Buyer Beware

We mentioned it briefly, but it’s worth repeating. A credible dealer should be your go-to. As far as research is concerned, there are a multitude of forums out there, populated by watch geeks. But if you decide to go the Ebay route, do so with a grain of salt. Yeah, you can probably find some good deals on there, but make sure the seller is up to snuff. Otherwise, you might just end up with a random estate sale piece that’s held together with rolled dice and crossed fingers.