I'm no pro, but I've done my fair share of gigging, teaching and misc. other music projects since high school. If you're starting from the bottom, be prepared to work for very little. Publicity IS a fair deal (though cash should be involved as well) when you are starting out. I played a restaurant gig once a week for an entire year right out of high school. The pay was pretty shit, BUT we got fed, had basically paid rehearsal time every weekend (because we were just wallpaper), and it led to many, many other WELL paying gigs, and something to throw on the unofficial resume. Once you start progressing, don't step backwards. If someone has paid you 150 bucks for a track, then don't do tracks in the future for less than that unless they've somehow worked some other perks into it.