You are, naturally, the person most familiar with your product. You know all of the ways it can benefit a potential client.
It doesn't matter how great that product is, though, if nobody knows about it. As P.T. Barnum said, "Without promotion, something terrible happens... nothing!"
Social Media
YouTube, Linked In, Twitter, these provide exposure that you can easily put to work. Marlo (my wife) recently helped a good friend set up his Facebook business account. He was reluctant to go outside of his comfort zone, and it took more than a little prodding to get him on board. Once it went live, though, he had 5 "Likes" in the first hour. Mind you, that happened without any promotion of the page. If he goes on to post videos/articles (such as the one you are reading), the effect will snowball. You just can't afford to ignore the exponential exposure these kinds of sites provide.
The Before and After
Some artists just want to do their show, and let it speak
for them. Sure, that may be a great way to get a potential client's attention initially, but the performance only lasts for 30-60 minutes. Both before and especially after the performance, you should be speaking with attendees and collecting business cards (assuming you weren't booked by an agent). Yes, this is basic networking, but there are plenty of activities that can distract you from this valuable practice (set-up and tear-down of your show, for example).
Taking It To The Streets
The most important piece of the promotion puzzle is to always be in "promotion mode". It's not always the concert producer or hotel manager that can use your services. A chance encounter with an old friend or making a new acquaintance could be that magical connection that comes out of left field, so keep your eyes open for opportunity every minute of your day.