If you're writing your own songs and playing gigs but aren't yet at the level to be signed by one of the big publishing companies, you should look into signing up with Sentric Music. Sentric is a company which provides all the services a music publisher usually offers, but rather than having a selective roster they are open to "any artist/songwriter of any level."
By signing up to Sentric you will hear about sync and licencing opportunities, for example to have your music played on a film soundtrack or TV advert, and if the Sentric team are impressed they might feature you on their blog or podcasts. But the main thing Sentric does is make sure you get the royalties you are owed, as every time your music is played live, on the radio or even in a shop you should be getting paid for it (even if it is a very small amount at first).
Signing up for Sentric doesn't come for free. Although there isn't a fee to join, you do have to pay them 20% commission on any of the income that they help you to receive, and 25% on any sync deals you make. If you or a friend have a good knowledge of how the royalty system works, you may be better off keeping track of things by yourself, but if it's totally new to you then Sentric could be a big time saver and allow you to focus on the music.
Find out more and sign up to Sentric here.