I have lived in Nashville in the past and have made my living by sound engineering over the last 7 years.
I've met more than a few professional session players in the area and their are a few things that immediately strike me about them.
1. Almost all of them have an outside skill or hobby of which they used to make a living at.
Literally, any pro you meet will have something they fall back on in lean times. Find an outside skill and develop. This might be difficult if you are practicing 16 hours a day 6 days a week but I bet you don't do that
Bassist Les Claypool was a carpenter, (so was Harrison Ford), outside skills to support yourself can greatly improve you confidence. Its hard to really be a "rock star" when you are worrying about rent.
2. Balance. A lot of successful songwriters don't necessarily have this, but most of the session & side men are very stable in their lives. Discipline.
3. Everyone gets one shot in Nashville. You ARE seen by the players if you play in town, and if you are decent you will do some session work. If you can't deliver the entire track in no more than 2 takes you will probably NEVER work again for a decade+ before your next shot. Be sure and be tight with a click. Everyone talks in this town. You screw up one session and EVERYONE will know it.
4. Be friggin awesome. Are you the best in your city at drums? In Nashville you will probably only be average, if not below average then. Remember, music Mecca's attract the Best of the BEST. If ANYONE in your town is better than you than you have a serious uphill battle ahead of you because the guy that THEY consider untouchably good will be competing with you for session work. PRACTICE PRACTICE PRACTICE and remember, people don't pay to have their friends play, when money is put out people want the best.
.02
P.S. If your friend mutters on about playing a show with Major Label Interest run like hell. It is the dumbest line known to man. Or do do it, if you didn't get sign they didn't want you. When I did sound in various clubs around the area they ALWAYS said at EVERY SHOW, "major label interest". That term is a peeve of mine.