The age old problem isn't it You haven't been very specific about what you want the traffic for but check my sig for good training, traffic and advertising options - including Free - and see if it meets your needs. Cheers, AllanJames (the StartBusinessMentor)
And do it gradually if the new Google Patent about detecting spam backlinks means anything http://forums.digitalpoint.com/showthread.php?t=1033155
If you looking to get traffich from search engines then the link building is the most important thing. If you want traffic in other ways you could do gerilla marketing or you need money to promote your site on websites with CPC, CPM or/and CPA program like CJ.
Here's a big list of social bookmarking sites: http://www.sta.rtup.biz/forum/topic/show?id=2084667:Topic:409 Submit your content there and start ranking for what keywords you want in the search engine and the traffic will come.
Spend some efforts searching and reading this or some of few million of other sites on the Net already answering your question.
Try to improve your SERPS. You will get all the traffic you need from SEs, so try to improve your ranking in SEs. Build backlinks that are relevant and add lot of content in your site.
Link building can generate much more traffic to your site. Good incoming links help generate higher Google rankings so peopel can find your site easier. Find other realted sites and see if you can put a link on their sites, or swap links.
adsense click comes from search engine like google,yahoo. So, create unique content in regular basis and SEO your website.
you need to be more specific to get significant response. There are lots of ways to increase traffic from link building, social networking and PPC to Link baiting and press release. Mostly depends upon the nature of your website.
Write articles Submit them to directories Post them on your blog ping them Bookmark them Build back links with directory submissions Post comments on blogs, forums, yahoo answers
I am a fan of article marketing...it gets high quality visitors, especially the ones that comes from the search engines. i use ezinearticles.com mostly