I would call, because agents do all their work on the phone, and do it repeatedly--the main thing is to remember that persistance and confidence are the things that pay off, and that good manners make no impact on an agent at all. To figure out which agents you want to contact, work backwards--look at the artists that have the kind of jobs you'd like, and find out who handles them, also, call the venues that you want to play and ask them which agents are usually in touch with them--

If you are in their faces all the time, they'll give you something just to shut you up--not the way you'd like to work, maybe, but at bottom, it's a business, no different from any other--