While it's tough to tell exactly how many people participate in a polyamorous relationship (that is, one that involves having more than one partner), it seems to be on the rise-or, at least, getting its time in the spotlight. According to a national Avvo.com study from June 2015, about 4 percent of the U.S. population admits to being in an open relationship, which equates to about 12.8 million people. Yep, million. So if you find yourself feeling curious about polyamory, and how to have a healthy polyamorous relationship, know that you're not alone-and read on to get the most important tips experts say everyone needs to know. (Related: 8 Things Men Wish Women Knew About Sex)

It's Not a "One Way or the Highway" Situation

First of all, there are many different kinds of polyamorous relationships, so it's important to know exactly what it is. "Polyamory is a state of open-heartedness and open-mindedness about having multiple simultaneous relationships," says Anya Trahan, relationship coach and author of Opening Love: Intentional Relationships & the Evolution of Consciousness. "Intimacy might mean sex and romantic connection, or it could mean a deep emotional or spiritual connection."

That open-mindedness is the key to a successful polyamorous relationship-and likely why so many people are now admitting to at least experimenting with it. "Many people across the globe are becoming wise to the [notion] that love is not bound by gender," says Trahan. When that happens, "we begin to question other things that are considered 'normal,' like the idea that the only way to have a healthy, intimate relationship is between only two people."

Which, if you stop to think about it, can make a lot of sense for someone. With approximately 38 percent of marriages ending in divorce from 2000 to 2014, according to the CDC, Trahan says a lot of people are broadening their horizons, so to speak. And Elisabeth Sheff, Ph.D., relationship consultant and author of The Polyamorists Next Door: Inside Multiple-Partner Relationships and Families, says it's a way for people to have more of their emotional and physical needs satisfied. "You're getting more needs met, and different needs met with different partners," she says.

It's Not Just About Sex

While it's easy to jump to the conclusion that people in polyamorous relationships love to have as many varied sexual experiences as they can, both Sheff and Trahan say that usually isn't the case. "Media tends to portray poly in a sensationalist way, unfortunately focusing narrowly on drama and sex," says Trahan. "But the poly people I know are deeply spiritual people, people who are compassionate, conscientious leaders in their community." Sheff agrees, noting that those practicing polyamory tend to crave more than sex in a relationship. Whereas people who tend to be a part of the swinging community, for example, are more focused on physical gratification, she says. (Did You Know Women Can Get Blue Balls Too?)

And sometimes sex doesn't come into the picture at all, says Trahan. "Many are emotionally or spiritually poly, meaning they are engaging in multiple deep relationships without sex," she explains. It's simply connecting with another person you can really count on, and prioritizing your relationship with them, without having to worry about whether you're having-or giving-an orgasm, notes Sheff.

But Sex Does Come Into Play

Of course, those who identify as polyamorous sometimes have sexual relationships with someone other than their primary partner, says Sheff. While it's not considered cheating, that doesn't mean there aren't rules. "Consent and honest communications are required at all times," says Trahan. And Tara Fields, Ph.D., marriage therapist and author of The Love Fix: Repair and Restore Your Relationship Right Now, says it's important to establish boundaries with your current partner before exploring, as the two of you may not be on the same page about what's okay and what's not, and that can make the relationship go sour fast. "It's all about trust, and you both need to be equally interested, curious, and willing to try it," she says. So answering important questions like, "What happens if you start to fall in love with someone else?" or "How much should additional partners be involved with our children (if you have any)?" should all be discussed and agreed upon before anyone moves forward, she says.

Protection is also of the utmost importance for the polyamorous, says Sheff. "They take a lot of care with testing and knowing their status, being really on top of using [birth control] barriers, and coming up with fun and creative ways to make those barriers sexy and interesting," she says. So protect your sexual health consciously by getting tested and asking your partners to do the same, then show each other your results. (Here's How to Ask Your Partner If He's Had an STD Test.) This should be done whenever a new partner is introduced for either person, says Sheff, as statuses can change without people being aware.

But Be Warned...

A common mistake people make when opening up their relationship to polyamory is thinking it will fix whatever problems you currently have with your partner. "If the relationship is broken, adding more people will not help," says Sheff. "If you're truly unhappy, it's a recipe for disaster and it's better to get out of the relationship and move on to new things than grab a life preserver." Why? Sheff says that because polyamorous relationships require honesty and constant communication-two things that usually shut down when a relationship is struggling-it requires you to face your issues. And if you're not comfortable doing that with one partner, then it's not fair to bring a third party into the mix.

"It's important to know the difference between 'here's an opportunity for growth and we can come out stronger and happier on the other side' and 'this relationship is just f-cked and it's not going to get better,'" she says. "It's hard, but it's something that needs to be done because polyamory rubs your face right in your issues."

Another reason not to jump into polyamory quite yet: You're not sure if it's what you really want. "You need to know your own boundaries or people will talk you into things that you don't necessarily want to do," says Sheff. If your partner wants to be poly, and you don't, it's time to re-evaluate the relationship. Don't be pressured if you're not into it.

Before diving in, Sheff suggests asking yourself these questions: "How does it feel knowing my partner is flirting with someone else?" "Am I comfortable being sexually involved with someone and understanding that it's not cheating-and same for my partner?" and "Does this go against any of my core beliefs or spiritual views?"

You May Want to Ease Yourself In

Because polyamory is usually an emotional investment, Sheff says it might be smart to instead define yourself more as monogam-ish when you first get started. "Polyamory tells other people that you're looking to fall in love with other people, but when you first start exploring you may just need to kind of figure out if non-monogamy works for you," she says. "That kind of phrasing, monogam-ish, lets people know, 'Hey, I'm just checking this out and don't necessarily know what I'm doing,' so then they don't get emotionally invested right away, either."

Then, talk about it with your current partner to see if they're even open to the idea before you do anything, says Fields. Otherwise, no matter what you say, it's going to come across as cheating. And if they're not cool with it, then you need to either walk away from the idea or walk away from the partner, she says. Trahan adds that, at that point, it might be in your best interest to pursue poly as a single person.

To broach the topic, Sheff says it's critical to start with reassurance. Saying something like, "Babe, I want you to know that I love you, I find you desirable and I'm attracted to you, and I'm happy with our relationship," tells him upfront that it's not about being unhappy with what you currently have-and the more specific you can be, the better. Then make it clear that you just want to talk about it, that you haven't done anything, and he can still trust you.

Some Best Practices

Figure out what kind of polyamorous relationship you want. One definition from one couple can be totally different from another's, says Trahan Polyfidelity, for example, means all members are considered equal partners who remain faithful to one another. Others prefer to have "intimate networks," where lovers are "labeled" as primary, secondary or tertiary, depending on the level of commitment that's involved. And then there's relationship anarchy, when you have multiple open relationships, but don't label or rank them.

Get educated. "There are a lot of great books out there on polyamory, like Wide Open and The Game Changer," says Sheff. "There are also how-to manuals you can check out and online support groups that can help answer any questions you have." Fields also suggests seeking guidance from a counselor, preferably one who is knowledgeable about and regularly works with polyamorous couples. Sheff, who is one of these counselors, says you can find a list of professionals on the National Coalition for Sexual Freedom.

Set your boundaries. It's important to know how both of you feel about certain situations, says Trahan, so covering topics like how much information your partner gets-and when they get it (do they want to give you permission before, know about it right after it's happened, or not want to know at all as long as you're not at risk?) is key to success. Other topics: If it's okay for someone other than you to have sex in your bed; if sleepovers are okay; who you can and cannot see (are exes off limits?); and if you have separate bank accounts that you use for finances involved with other people (going on dates, vacations, etc).

Always be ready to renegotiate. A polyamorous relationship that works for you rarely ends up being what you dreamed or fantasized about, says Sheff, so keep an open mind. And if you're going into this with a primary partner, Fields says to always keep checking in with each other as you take new steps. "Just because you're open to exploring doesn't mean you're going to be comfortable with every facet that your partner is, or that you have to follow-through," she says. "Do what makes you both comfortable, check in, and discuss what's next. If one of you starts to feel anxious, then you talk about what's best for both of you."