Despite a particular organization’s claims that your free work could lead to bigger and better opportunities, you should approach with caution. Giving away your time, energy and content for free could interfere with your ability to earn a living. It could also devalue your brand and it may cause you to get burned out.

But, there are some opportunities that could help launch your career—even when you don’t get paid for them. And over the years, I’ve become better at recognizing which unpaid opportunities to accept and which ones to pass up.

Here are four times working for free might make good business sense:

1. When the opportunity will give you real-life experience.

If you’re launching a photography business side hustle, don’t expect to get paid for your first gig. Agree to take wedding photos or business head-shots for free to build your portfolio.

Similarly, if you want to become a speaker, consultant, or coach, working for free for a while can serve as opportunities to sharpen your skills. Once you get more experience, you can start charging for your services.

Set a limit on how many times you’ll work for free. If you’re still working for free after 50 unpaid gigs, you have a hobby as opposed to a legitimate income source.

Think twice before contacting strangers to offer your services for free. Reaching out to them might backfire if you come across as desperate. People won’t take you seriously when you’re announcing your time and efforts aren’t worth anything.

2. When the experience will give you legitimate exposure.

Whether it’s a podcaster looking for free content, or an organization asking you to host a webinar for its employees, invitations to work for free often come with a promise of exposure. But not all exposure is created equal.

If your friend asks you to create his website for free in exchange for a small credit in fine print, will that help you gain more clients? It could if your friend is a famous blogger with millions of readers every month. But, even then, it’s unlikely you’ll be overwhelmed with new customers.

If, however, your friend says he’ll write a blog post about why you’re the best website creator ever, the exposure might be worth it. A clear call to action read by millions of people could give you a huge boost in business.

Too often, however, people who ask you to work for free will give you vague information about how this exposure will help you. They say things like, “There will be influential people in the audience who may hire you,” or “You can sell your products to our members.”

So it’s important to ask specific questions about the exposure you’ll gain. Find out who your audience is and what you can realistically expect to gain. If they’re willing to tell you who else has worked for them for free, contact those people to find out if their efforts were worthwhile.

3. When you’re supporting a cause you believe in.

When there’s an opportunity to get involved in a cause you believe in, it may make sense to focus on what you can give, rather than what you will gain. Just make sure you don’t expect your volunteer work to catapult your career.

Set limits on how much time you’ll donate. Whether you decide to make one free logo a year or you commit to speaking at three events each year for free, a concrete limit will prevent you from overextending yourself.

Then, when someone asks you to donate your time, you can say, “I’ve already reached my allotment of how much work I can do for free this year.”

4. When the affiliation will be an impressive addition to your CV.

Although you might assume the biggest companies will have the most money to pay, that’s not always the case. Interestingly, many high profile organizations request people work for them for free, even though they have deep pockets.