So you wanna be a producer?

It helps to start young. And it doesn’t hurt if Harold Prince lends you a hand.

Legit producing is a tough business to break into, especially since the community of Main Stem producers is, as many in the industry will tell you, mostly a loose group of independent businesspeople.

That means there’s no set training, and there are a variety of ways to launch an above-the-title career.

One route: Get a head start, like Rachel Helson, a producer of “Reasons to Be Pretty.” She’s not just young in the broad, “under-40” sense of the word — she’s 20.

Or, like 29-year-old Orin Wolf, you could get a leg up through the T Fellowship for Creative Producing, co-founded by Prince. As the culmination of his fellowship, Wolf shepherded South African play “Groundswell” to a well-reviewed Gotham production from Off Broadway’s New Group.

“The point of the exercise is ultimately to bring plays back to Broadway that do not have 25 names over the title, and that pay back,” says Prince, 10 of whose 21 Tonys are for producing.

Named after Phoenix Theater co-founder T. Edward Hambleton, the T Fellowship reps a partnership between Columbia U.’s School of the Arts, which runs the program, as well as the Theater Development Fund and the T Fellowship Committee, including Jack O’Brien, Margo Lion and initiative co-founders Prince, Geraldine Stutz and Ed Wilson.

Encourage by Prince, Wolf thought creatively. “Groundswell,” a three-character, single-set play by Ian Bruce, arrived in Gotham with a deal for the film rights already in place with a Dutch filmmaker. A commercial future for the play also is in the offing, with London looking like a strong possibility.

Wolf studied to be an actor but switched roles soon after a director yelled at him for worrying about aud comfort in an un-airconditioned black box. “He said, ‘If you want to worry about that kind of thing, go be a producer!’ ” Wolf says.

As for Helson, about to finish up her BFA in drama from NYU’s Tisch School of the Arts, she was a child actor in Equity productions in Louisville, Ky. When her aunt was diagnosed with breast cancer, she decided to produce a Komen Foundation fund-raising perf of “The Rocky Horror Show.”

Her philanthropy, plus an internship with Bernard Telsey Casting, led to her involvement in “[title of show],” for which she was an associate producer, and “Reasons,” which lists her and partner Heather Provost above the title.

“I talk to everyone I know about a project,” she says of her fund-raising technique. “Money comes from the weirdest places sometimes.”

Helson adds she learned by doing. But for aspiring producers looking to take a class, one of the closest approximations of producing school available is the Commercial Theater Institute, which runs seven programs, including a summer session over a long weekend in July at the Eugene O’Neill Theater Center during its National Playwrights Conference.

With the guidance of knowledgeable guests including producers, marketers and legal types, participants are tasked with drawing up a business plan for one of the new plays or musicals developed at the conference. Then they pitch it to a panel that includes Tom Viertel, chair of the O’Neill Theater Center, and Jed Bernstein, the program director of CTI.

With real projects in the mix, theories of producing are applied to real-life test cases.

“It’s like working with live ammo,” Bernstein says.