One of the best ways to get traffic is to search engine optimize your website. When people want to find something, they generally go to the search engines to find relevant websites. If your website is at the top of the search engines for certain keywords, you'll be able to get a lot of targeted traffic and help your list grow in the process.
There are many different aspects to search engine optimization that you need to pay attention to. The first thing to do is research keywords that are related to your niche. It is ideal if these keywords are highly searched and have low competition in the search engine results.
Then, create content based around these keywords that will help you rank more highly in the search engines. You should also work on getting backlinks to your website, to boost your credibility in the eyes of the search engines. Backlinks are nothing more than getting OTHER websites to link to yours, preferably ones that are established, quality websites.
If you don't have the time to do this SEO yourself, check out RankCrew. I've used them, they do exactly what you pay for, and they do it quickly.