It’s the corporate equivalent of a midlife crisis, and here’s how it happens. You’re in your forties, a senior vice president at a big company, where you manage scores of people and collect a huge paycheck. But every time your company acquires a startup you see a bunch of utterly ordinary people become ridiculously rich.

Why shouldn’t you cash in too? Get the Botox, color your hair, and soon your preternaturally youthful face might adorn the leadership page of some 100-employee outfit that nobody has ever heard of—where you’ll await your life-changing jackpot.

It’s a scary leap—or should be. Most startups flame out, or just muddle along. Your chances of spotting a unicorn, pre-horn, are incalculably small. But if, knowing that, you still want to toss aside your cushy job, at least listen to corporate vets who have made the transition. Here’s their advice on how to do it right.

Think like a VC.

Would you invest in this company? A startup job is an investment, after all: Venture capitalists may wager money, but you’re staking something more precious—your time. And unlike VCs, you can’t spread your risk by betting on a bunch of companies at once. Start with TAM. That’s “total addressable market,” and if it’s not big enough, there’s no point in talking. It’s the first number you’ll get from the VCs backing the company.

Don’t join late.

If the startup is past Series C, you might not have enough upside to make it worth your time, says a friend of mine. (It’s sometimes possible to join late and strike it big—for example, if you’re a CFO joining a company that needs your expertise to float an IPO. But for most people, joining late means less risk but also less reward.)

Team, track record, and tech.

Have the CEO and head of engineering done this before and produced a successful exit? Is the technology really special, or just a me-too product?

Read More: My Year in Startup Hell

Work with people you’ve worked with before.

You’ll do better with people you trust. If that’s not the case, then …

… Negotiate a strong severance package before you join.

There are too many ways that a startup gig can go sideways. If the startup won’t agree to hefty severance, pass.

For more on startups, watch this Fortune video:

Meet the board.

Do the board members ­support the CEO and the rest of the team? What’s the ­company’s biggest challenge? The directors (typically the VCs who have backed the company) might have a better perspective than management.

Beware the quick offer.

It’s flattering, but also a red flag. Talk to at least 10 people, especially those who will be your peers. Figure out the culture and whether you will fit in.

Know your price.

For every role in a startup there is a going rate—­meaning how much equity and salary you should get, based on your title, the stage at which you’re joining, and location. You’re a vice president of ­engineering coming in at Series B and the job is in San Francisco? There’s a number for that. VCs track data from portfolio companies and share it with one another. Arm yourself with this information, or you might leave money on the table.

Finally, look inside.

Be honest. You might not be cut out for startup life. It’s better to admit that now than to make a huge mistake. If you do stay, still consider getting the Botox and the hair color. You’ll enjoy all the big-company perks—­including the assistants, the first-class flights, and the five-star ­hotels—while ­shaving a decade off your appearance. Best of both worlds. Savor that.

Dan Lyons is the bestselling author of “Disrupted: My Misadventure in the Start-Up Bubble.”

A version of this article appears in the November 1, 2016 issue of Fortune with the headline “Look Before You Leap.”