My first point of contact is by seeing somebody live or looking at a myspace account.
This is a good example of a myspace account that would help me to see if I wanted to book somebody or not.
The link is to a Local band and it tells me pretty much what I want to know. Songs/video of them on stage and who the band members are and a short Biog with some short acknowledgements of their prior gigs.
I don't see any bullshit on this website.

http://profile.myspace.com/index.cfm?fuseaction=user.viewprofile&friendid=105978061

From such a website I can get all I need and respond accordingly to an e-mail requesting a gig from a performer.

The e-mail should not be a spamming job, where you send one e-mail out to all organisers.

The e-mail should be short and too the point, requesting the possibility of a gig and a link to your Myspace account.

I hate getting all the mail sent to me with Cd's and promo material. It fills my house up and is not good for the world.

Don't cold call unless you are very good at selling yourself. Its embarrassing for you and the organiser.

Otherwise very much like Banjiman says.