Richard Branson says the “missing link” between a “promising businessperson and a successful one” is often a good mentor. And he should know.

If not for the “invaluable advice and guidance” from Branson’s business mentor -- the bullish founder of Laker Airways, one of the first no-frills long-haul airlines -- the self-made British billionaire might never have gotten Virgin Atlantic off the ground.

“It’s always good to have a helping hand at the start,” Branson says. “I wouldn't have got anywhere in the airline industry without the mentorship of Sir Freddie Laker. Now, I love mentoring young entrepreneurs.”

Mentors can help you take your startup from surviving to thriving. The benefits of consulting with the right one are practically limitless.

Here are 10 essentials to consider when working with your business mentor:

1. What questions should I ask my mentor?
Before you spring too many questions on your mentor, take the time to get to know him or her first.

“Learn about their individual stories,” suggests Samantha Albery, director of MicroMentor, a free nonprofit business mentorship service for entrepreneurs based out of Portland, Ore.

When the time feels right, begin by asking your mentor about herself. What is she passionate about in business? What are her core professional competencies and how did she develop them? How did she achieve success? What key lessons did she learn throughout her career?

Once you’ve established an open, honest and comfortable line of communication with your mentor, Albery says it’s also OK to turn the tables and ask her about you. What does she see as your strengths and weaknesses? How does she think you can improve?

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2. What’s the best way to communicate with my mentor?
By simply asking her how she prefers to talk -- by phone, email, video call (Skype, Facetime) or in person. Agree early on in your relationship how you will communicate with each other and how often.

If your mentor’s schedule or preferred method of connecting doesn’t work for you, it’s probably time to look for another mentor, Albery says.

3. How often should I hit my mentor up for advice?
It depends on how formal or informal your relationship with your mentor is.

If you’re connected formally with a mentor through a mentoring program, Albery recommends scheduling a weekly or bi-weekly meeting. Carve out up to an hour per meeting to work on concrete objectives together.

With an informal mentor -- someone you know through your own personal or professional networks -- it’s best to approach the mentor more personally. For example, offer to buy her coffee or invite her to lunch, says Albery. But not more often than once or month to once every three months.

Informal mentorship or not, contacting your mentor too often can lead to burnout and, eventually, she might not want to work with you at all.

4. Is it OK to let off steam with my mentor, to openly discuss frustrations and challenges with her?
Absolutely. Having a mentor you trust and respect, to listen to you and to help you think through difficult times is critical, especially when you’re launching a startup, says Christine Tsai, partner at 500 Startups, an early-stage seed fund and incubator program located in Mountain View, Calif.

“A mentor is someone you can lean on for advice and learn from,” she says. “Having someone you can turn to that isn’t your co-founder, even if it’s just to rant or complain, is immensely helpful.”  

5. Should I run my business plan past my mentor?
It’s generally best not to ask your mentor to do any real hands-on “work” like this for you.

However, asking her to perform a light read and review of your business plan for basic feedback on your overall strategy is typically acceptable, Avery says. Requesting that she do a deep-dive analysis of your business plan, complete with written edits and suggestions, generally isn’t.

6. Is it poor form to ask my mentor for business leads or to connect me with an influencer in her network?
It’s OK to occasionally ask your mentor for a professional reference, Albery says, but she doesn’t recommend ever asking her for an introduction to someone within her network, especially not to so you can make a sales pitch or solicit an investment.

“I would advise extreme caution when asking for anything but advice from your mentor,” Albery warned. “The most common challenges that we see with mentoring relationships is when it moves beyond the realm of mentoring and into more of a business transaction.”

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7. Is it OK to ask my mentor for advice about my personal life (or to ask her about hers)?
Tactfully asking your mentor how she maintains a healthy work-life balance is acceptable, but it’s generally not kosher to ask “probing or nosy questions about their personal life,” says Tsai.

On the flipside, you can occasionally ask your mentor for advice on how you should deal with a specific personal problem you’re going through, within reason, she says. “But try to keep the relationship business-focused.”

8. Should I ask my mentor about times she might have failed?
Probably not directly. Instead of specifically asking your mentor about her failures, which might come off as gauche or tacky, ask her to tell the backstory about how she got to where she is now. What challenges did she come up against and how did she persevere?  

If your mentor trusts you and you’re able to have candid conversations together, she might voluntarily open up about her career setbacks, Albery says. “Listen carefully so you learn how their experiences are applicable to your own situation.”

9. What are some appropriate ways to thank my mentor?
Gifts aren’t necessary, says Tsai. Simply saying thank you is enough, along with demonstrating respect for your mentor’s advice and time.

“What will be most appreciated is acknowledgement of the mentor’s advice being helpful, not being a pain in the ass, and respecting their time,” she says.

Tsai says giving your mentor a small gift during the holidays is appropriate, however, if you’re so moved. You might also consider treating her to lunch, but neither gesture is “necessary or expected.”

10. What’s the biggest mistake to avoid when working with a mentor?
It’s simple. Disrespecting your mentor’s schedule and, worse, breaking her trust, Albery says.

“Arriving late, not arriving at all, or not following through on a promise is a surefire way to lose a mentor.”

Also, don’t call your mentor just to casually catch up, Albery cautions. Always have specific, business-related questions and talking points prepared that you would like to gain her input and advice on. After all, that’s the whole point of having a mentor.

Related: 10 Questions to Ask When Determining Your Salary