You can register with the search engines and directories. There are several good services out there to choose from. Here's some tips I've picked up along the way.
Newsletters are one of today's best marketing tools.
It is a credible source of information. The key to doing a good newsletter is to give your readers information they can use. Make it worth their while to read. Be careful not to make it one big ad for your company. Lastly make sure you only send your newsletter to people who want it.