[Rogerh91]

I think of two things when it comes to this question: the notion that you should regard relationships as "lines and not dots", and how to get meetings with people too busy to see you.

Steve Blank has a great article about how you need to provide value to even begin getting into somebody's space. http://steveblank.com/2013/08/12/how-to-get-meetings-with-pe...

Now you might say, I'm a student, what could I do? But there's a lot you can offer, from your story and perspective to the skills you have. Even just writing from the perspective of somebody offering value rather than just trying to take it makes it easier for you to get meetings with the mentors too busy to see you--the kind of mentors you should aim for.

Starting a relationship is always easier than maintaining it. You want to make sure you could grow with the person you're reaching out to, and that ideally, the conversations you have with them will be mutually beneficial. After a while, you'll be learning from them and they'll be learning from you as well--if you plan for that relationship rather than sitting back and trying to grab a "mentoring" session you'll start seeing your thinking about mentor dots evolve into long-lasting line relationships.

My last note on this is that it's also a lot easier to learn from people if you're working for them.

To sum up

1) provide value to everybody you talk with 2) think long-term 3) work for people you REALLY want to learn from