I got an email today from a 19-year old guitarist from Alabama who wants to be a session guitarist. He wants to go to Musicians' Institute in Hollywood, but is overwhelmed by the expense that would put him into debt for decades. He asked my advice, so here it is:
School won't give you much you can't give yourself, if you're motivated. All the knowledge in the world is out there in books and videos available for $0-$100.
You could be a disciplined monster and dedicate yourself to 4 hours a day of intensely focused practice, devouring every instructional resource out there. Learn to play along with everything from jazz to bluegrass to classical to shredding metal. Study every guitarist you've ever heard of and learn how to imitate them. So when someone says, “Give me a Jeff Beck style slow tremolo tearjerker,” or “We need a driving 12-string acoustic stomp like Leo Kottke with Busted Bicycle.” - then you know what they mean and how to do it.
Besides just imitating the virtuosos, you should be able to be a tasteful rhythm guitarist for many different genres, including samba, James Brown funk, Delta blues, dreamy new-age, etc.
All of this costs you almost nothing. You can do it at home while keeping a part-time job to save some money.
Give yourself a future goal, like “By my 21st birthday I'll be able to play, note-for-note, the 3 definitive pieces by each of the top 50 guitarists across all different genres. And I will have saved $10,000.” Work your ass off to meet or surpass that goal.
Then on your 21st birthday, move to LA or NYC. Get a cheap apartment right in the middle of everything, and commit yourself to learning the social skills needed to be the guy that people call. It means a few hours a day of meeting everyone you can, being around the studios where people are hiring session musicians, being a good listener, being positive and helpful, keeping in touch, etc.
I made a living as a session musician in NYC for a few years. I'm a good guitarist, but I swear the reason I kept getting called is I would find a way to appreciate whatever crap they played me, telling them that it's awesome. It was a white lie but a good one, because people can be really insecure in the studio, and need encouragement.
Be humble and constantly learning, understanding you've made a many-year-long commitment to mastery. Some may scoff at you for being the new kid in town, so agree with them, respect their experience, and make sure they know you're committed. So few really are, that you're sure to stand out.
Do some research to find out who the top session guitarists in town are, and find a way to meet them. Let them know they're your role model and ask for advice. (Like you did with me, just now! Pays off, doesn't it?) :-)
Good luck. Let me know how it goes.
In Japanese: セッションミュージシャンを目指す19歳のギタリストへのアドバイス