Asking someone you know to mentor you

Example of writing to a known contact (someone you already know and/or have interacted with):

Dear Susan,

I have very much enjoyed and learned from the conversations we have had in the past, and I would like to ask a favor of you based on my respect for the way you have developed your career. I am at the point in my own career where I feel I need some mentoring to more effectively develop my management skills so that I can prepare to move into a leadership role.

I was hoping that we could meet for coffee to discuss my current needs and see if this is something you are interested in and available for. 

In this mentoring relationship, I am proposing to meet with you for about 60 minutes once a month to discuss your counsel regarding areas I should address. I would put together a meeting agenda for each get-together, make a list of any follow-up items that come out of our discussions, complete the action items during the next month, and report back on my progress.

I know that your schedule is an exceptionally busy one, so if it simply isn’t possible to work this type of commitment into your other activities, I certainly understand. In that case, thank you for considering this request, and I will simply look forward to our future conversations!

Best regards,