if you do a search on this forum you can find plenty of ideas but primarily these are the main ways
1. You can also add an RSS subscribe button/link in a high profile spot on your site
2. Press releases
3. Article submission
4. Forum Posting with a signature to your site
5. Directory submission
6. Tell everyone with whom you communicate
7. Post ads to free advertising website
8. Blogging and Blogging comments
9. Social Bookmarking/networking sites, such as StumbleUpon, Digg, etc
10. Paid advertising
11. Contests, giveaways, etc
12. Business Cards
13. Trading Links with affirlates or related businesses to build Pagerank
Also in addition to these you can also add a Stat counter on your page to find statical data about your website including where your users are coming for and what keywords they use to get to your site etc.
The Free stat counters i recommend is Google Analytics, StatCounter, OneStatFree