The 5-Step Guide To Actually Making Money Off Your Luxury Fashion Purchases

I'm a high-key beauty snob and a low-key fashion one. I might not store my Helmut Lang and Derek Lam the same way I store my MAC lipsticks, but I'm just as anal about who gets to touch them. I'm a huge buy-and-resell gal.

For example, take my Urban Decay "Alice in Wonderland" Book of Shadows from 2010. I bought it, forgot I had it and then re-sold it on eBay for around $200 about a year later. Bitches love limited edition eyeshadows.

The same holds true for fashion. I buy limited edition items with the purpose of reselling. Basically, I'm always first in line for Target collaborations.

There's money to be made here. According to Fashionphile founder Sarah Davis, handbags and accessories are the best investment. The price of the Chanel Medium Classic Flap Bag, for example, has increased nearly tripled in under 10 years.

Not sure where to start on the resale market? Here's what you need to know.

1. Keep an eye out for collaborations between low and high-end brands.

High-end designers and labels -- think Lanvin and Alexander Wang -- love to collaborate with mass market brands. The average consumer can buy something that's high end (ish) on a budget, and the designer gets exposed to a whole new group of clientele.

Usually, these items are produced in extremely limited quantities. Once an item is sold out, it's gone, and you better snatch it before it's permanently out of reach. Take, for example, the H&M and Balmain collection released last year. The pieces sold out faster than most of us could hit refresh, creating the recipe for a perfect resale.

Those telltale “special” pieces -- think the Balmain embellished dress, the Maison Martin Margiela bodysuit -- always make a killing once the store sells out. That Balmain dress is now on eBay for $1,800, if you want to spend two months' rent.

2. Know the classics.

Old-school investment pieces like Hermes Birkin bags, Cartier watches and Goyard totes are the epitome of luxury. They're the pieces that reek of exclusivity and intrigue because they're not highly publicized or easily replicated.

Take, for instance, cotton, hemp and linen Goyard. Each piece is totally unique. Even if you want to purchase one on resale, you'll have to pay thousands.

Those fabled pieces will always be in vogue because they're iconic and unchanging. Additionally, there's consistent demand for them, so prices increase season after season. According to a Baghunter study, the Hermes Birkin is more valuable as an investment than either gold or the S&P 500. No wonder Samantha Jones had to pretend to be Lucy Liu to get her hands on one.

3. Don't throw anything away.

If you want to resell your Saint Laurent blazer, you'd better hope it still has tags. The same goes for purses -- without the authenticity card and the dust bag your purse came in, you can kiss a couple hundred bucks goodbye.

Authenticity and good condition are the two most important factors affecting your resale game. People are afraid of being duped, especially if they're dropping hundreds (or even thousands) on an item they probably haven't had the chance to view in real life. You'll want to provide as much insurance as you can that you are to be trusted as a reseller.

It doesn't matter how much you swear you bought your Balenciaga at Barney's, because you need proof. The tags, boxes and cards act as your proof of purchase.

4. Wait it out.

If you wait long enough for your piece to become a vintage find -- usually no less than 20 years -- you can expect a pretty substantial return. William Banks-Blaney, owner of William Vintage in London, told CNBC that there is "between a 10 and 20 percent year-on-year uplift in good pieces of vintage."

Just make sure you take substantial care for your pieces. Keep the soles of your Louboutins clean and red -- no scuff marks -- and store everything in garment bags to prevent damage. Make sure your furs are stored in a cold space, as low temperatures slow down the biodegradation process.

Basically, care for your investment piece with the knowledge that each tiny stain can cost you money.

5. Ignore trends.

By now, you know classic pieces trump all. Trendy pieces -- think normcore, athleisure or any particularly bizarre patterns -- will only be "cool" for a season or two at most. The likelihood of them appreciating in value is super slim.

Limited edition pieces are the exceptions to the rule, however. If you opt for a bright green Chanel because you have a hunch it'll sell out quickly, for example, resell it as soon as you see it doing well on sites like Tradesy and The RealReal. Check eBay, too. Waiting around might run the risk of your trend piece running its course, rendering it worthless (or at least, worth less than you paid for it).

For example, take a look at the Isabel Marant sneakers. While they were a huge hit several years ago, no one really wears wedge kicks anymore. If you were a reseller, you had to act quickly, otherwise you're sitting on a pair of kicks worth nearly $700.

Fashion investing is just as high stakes as the stock market: You have to know when to sit it out and when to pounce. And they say us fashion girls can't do math.