What is a mentor?
A mentor is "a wise and trusted advisor". A mentor will be someone working in your industry, who has more knowledge and/or experience than yourself whom you can turn to for personal advice. Using a mentor is a fabulous way to learn all the things that have never been written down formally and are best imparted by someone who's "been there". Your mentor may also be able to give you a little boost with connections they've established (since they've been in the industry longer than you). Mentor does not mean manager, although your manager could also be your mentor. Mentors volunteer their time, often to "pay back" good deeds that someone did for them earlier in their career.
How do you find or pick a mentor?
Is there someone you admire, who is doing something in line with your own style? Contact them and see if they'll be willing to mentor you a little. This person does not necessarily have to be in your city or region - technology has made it much easier to converse across miles. If you really don't have any ideas, contact SRIA or others the industry for suggestions. Your prospective mentor doesn't have to (shouldn't) be a superstar - just someone who has something worthwhile to share with you.
He (or she) will have to like you and your music - that's a subjective thing - and he simply may not have time to give at this point in his life. But it's always worth asking. I would approach the person - if possible arrange to meet him at one of his shows - let him know you are seeking a mentor and why you would love to be mentored by him (flattery works but don't gush), then find out what he needs to make his decision (your demo, some time to think it over, etc.), and when you can contact him again.
I would try to reach the artist or person you are soliciting directly (as opposed to through a booking agent or manager). It's a personal relationship thing, so the two of you have to hit it off.
Tip: I would be more likely to mentor someone if they have done their research on me, and thus know why they want ME to mentor them (make them feel like your number one choice, not just someone you drew from a hat). It has to be a case where you honestly respect the person's music and/or reputation in the industry; after all, you are striving to be like them in a way!
Expect of the mentor (for your situation, which is basically developing your artistic career)...
- that they'll come to see you perform live at least once (this may be where they decide if they can mentor you, or not) - but don't expect them to travel a great distance to do so
- that they'll be available to answer your questions by phone, email, and/or occasionally via a personal meeting
- that they'll provide you with realistic and honest solutions to your queries
- that if the relationship is not working for them, they will bow out gracefully rather than dodging your calls
- that you will cover cost of communication (i.e. long distance phone calls)
- that you will restrict your calling and communication to only when necessary, and when convenient for the mentor (i.e. not after 10 pm, or not daytimes during the week).
- that you will take the advice offered by the mentor (if you consistently do not take their advice, find yourself a new mentor, or re-evaluate your reasons for wanting one)
- that you consistently thank the mentor for their time, and provide credit where it is due (album liners, sending thank you notes, etc.)
Do not expect...
- the mentor to incur costs for you - whether it's a long distance bills, travel, etc. If you're scheduling a lunch meeting, you pay for lunch.
- the mentor to do the work for you (i.e. tracking your single, writing your press release...), however, they may choose to (for example) make some calls or meetings on your behalf if they have a good connection.
- to be included in your mentor's career. Mentoring is one thing - accepting someone as a co-writer is entirely another. They may invite you to their shows and get you in for free; they may invite you to rehearsals; they may at some point invite you to write with them. But only when they are sufficiently comfortable with you.
Always remember that the mentor is doing you a favour, and you should make it as low-maintenance for them as possible. Don't call with stupid, repeat questions (not that you would); don't call outside of your agreed-upon hours, and don't expect them to keep mentoring you if you never listen to a thing they tell you! If you've left one message and can be reasonably sure they received it, that's sufficient...don't keep calling. (Yes, this has all happened to me!)