Mentoring is hard.
Mentoring is also a more significant part of the economy today than since, perhaps, apprentorship in the craftsman age.  Why? The rise of entrepreneurship and the freelance economy is similar to the craftsman age since as the very structure of the economy undergoes massive transformation, workers are increasingly required to find their own means of making a living.
During the Industrial age, most labor was focused on optimizing repeatable tasks.  Repeatable tasks are taught. Mentoring was more focused on developing leadership qualities, responsible for corporate management.  See Blank’s Sloan vs Durant. Today’s mentoring must teach leadership, too, but additionally, the nature of entrepreneurship.
The requirements for high-quality mentoring have changed, but in most environments outside of major tech hubs, the practice of mentoring has not kept pace.
The successes, for example, of Y Combinator and Tech Stars can be attributed directly to the quality and rigor of their mentorship.
Of course Y Combinator and Tech Stars have access to world-class entrepreneurs and experts and I’m guessing their mentor programs have evolved as they found what worked and what didn’t.  While the rest of the world doesn’t likely have the same access, we certainly can improve our mentoring and mentor programs.
So, two posts: First, I’ll try and avoid the mundane while discussing what makes a good mentor.  Second, I’ll lay out what a good mentoring program might look like.
Here are my keys to successful mentoring:
1) Teach, don’t Tell
The role of a mentor is not to criticize a business model.  Too often I hear comments to founders that add up to “that’s a terrible idea” or “that will never work.”  The mentor might be right. If truth be told, the mentor probably is right. But truthfully, that’s not because the mentor knows this to be the case. It happens to be the nature of the beast that if you predict failure, you’ll be right 9 out of 10 times.
The role of the mentor is not to replace the founder’s business model assumptions and market guesses with his own. The mentor should teach the founders how to test and validate (or likely invalidate) those assumptions.
I recently had a conversation with the leader of a local mentoring organization who insisted that it was her responsibility to prevent founders from wasting their time on ‘bad ideas.’  This is a problem.  You are not the arbiter of good ideas.
Your expertise may even be blinding you! (More on this below.)
If by mentoring, you mean sitting around a table with other ‘mentors’ criticizing business models to impress each other, please find another way to spend your time.
You’re not helping.
The best mentors teach the founder skills, so that she can learn whether the idea is good or not.
2) Focus  Your  Advice
Mentoring advice should be focused on specific needs the founder has.  This relies, of course, much on the founder, who should articulate a clear objective for any particular mentoring session.  It’s also the founder’s responsibility to find the most appropriate mentor to give advice for that specific objective.
Still, mentors should avoid giving general, expansive advice. I wince whenever I hear “Have you ever thought of…” openings to ‘advice’.  Sometimes this is appropriate to try and get founders to think about things in a new way, but more often than not, the conversation is being hijacked, off an a tangent unrelated to the objective.
Successful mentors are often analytical people. They’re used to breaking complex ideas down and coming at problems from different angles.  This is clearly useful in many circumstances, but be wary of overusing this ability in unconstructive ways.
The best mentors have the ability to ‘score’ their confidence level of the advice they give. In other words, they will say, ‘Listen, I’m just shooting from the hip here, I don’t truly know, but I think…’ OR ‘I’m pretty confident about this, because…’
3) Challenge Assumptions
In my view, one of the keys to getting a new business off the ground is to understand what is known versus what is unknown.  Many new entrepreneurs are taught to pretend to know it all.  After all, the thinking goes, if you don’t know, you’re not really ready to launch the business.  (For documented not-knowing, see business plan.)
In our book, The Lean Entrepreneur, we attempt to help founders articulate where on the “Innovation Spectrum” their ideas lay.  Those toward the disruptive side face more “unknowns” and those toward the sustaining side know significantly more about their markets. A central premise of the lean startup is to divide your activities such that your focus on executing on that which is known and learning that which is unknown.
Mentors can help here in a couple of ways:
First, openly challenge Founder’s thinking by exposing non-validated assertions.  It’s great that entrepreneurs are passionate about their product idea; they need to be. But conviction based on passion creates a faith-based startup that is doomed to fail.
Second, mentors can help founders devise experiments, provide introductions to customers, or come up with other ways to learn what is unknown, such as looking for analogs in the marketplace.
4) Beware Being a Domain Expert
Sounds counter-intuitive, I’m sure. Aren’t you supposed to bring your domain expertise? In The Lean Entrepreneur, we talk about how business activities vary depending on where a particular product sits on the innovation spectrum.
Once the bastion of franchises and medium to large enterprises, startups do a lot of incremental innovation these days.  That’s fine; big businesses are outsourcing some of their sustaining innovation. Domain knowledge is particularly helpful on the sustaining side.
But if you try to apply your industry expertise to a startup that is trying disrupt that industry, you’ve got a problem:
To industry insiders, disruptive innovation looks like bad sustaining innovation.
You might want to read that again. This is why “experts” love the phrase “It’ll never work!”  That’s the last thing a Founder needs is to hear from an insider.
Not that there isn’t some knowledge to be leveraged. If you can remove yourself from the emotion of seeing your industry potentially disrupted, you can share market knowledge, contacts, and other tips and hacks.
And yes, the mentee should be aware of this when seeking advice from industry experts, but also, the best mentors are those who are aware of their own biases and steer clear of areas in which they have a personal stake or an emotional connect to.
5) Teach Entrepreneurs how to be good mentees.
I have often heard myself complaining that those I’ve mentored rarely follow up.  I could be I wasn’t a good mentor for these Founders, but I hear this often from other mentors and my ratings have always been high.
It recently occurred to me that many entrepreneurs need to be taught how to be mentees.  So while many mentors view follow-up as a indication of “entrepreneur-worthiness”, mentors who are interested in a particular startup or founder, should instead reach out themselves.
Reaching out doesn’t mean, however, ‘how’s it going?”  Reaching out is mentoring: it’s something like:
‘Hey, I haven’t heard from you in awhile.  If you really wish to take advantage of my  (or other’s mentoring), you need to be way more proactive.  Here’s what I recommend:

• After each mentoring session, write an email thanking the mentor and summarizing the conversation;
• Follow up within a week with specific action taken on the advice or why action wasn’t taken;
• Write a monthly update on company status, needs, achievements, etc. Send this to all mentors, investors, and other interested persons.

You won’t hurt my feelings if you have chosen to work closely with other mentors, but I think the above advice will serve you well.’
Exceptional mentors ping the entrepreneurs. It’s related to teaching Business Development, so you are actually developing a skill.