Give a free car to every visitor and it will be one of the most popular sites in no time. I mean, you should make your question more specific...
This is the question... Some time ago you just needed to create content. But now its not sufficient...
1st: SEO because every one use search sites. 2nd: link exchange/buy from same niche of your site. 3rd: Article submissions.
I've been getting traffic from social networks. Posting in Facebook and Twitter is a good way to promote sites and links.
Article submission, press release submission, forum posting, blog posting etc. are the best ways of promoting your website
may be you should learn about seo, so you dont need to buy or pay for anythink to increase your SEO. hehe
SEO= search engine optimizations: meaning: forum posting (digitalpoint), article writing(ezinearticles), link biulding(link market), blog commenting (varies from niches to niches), sitemap for your site (to get google index more links for better chances to get visitors), and lastly, my favorite, for increasing alexa rank (autosurf programs). This is the meaning of SEO for me.