As you can imagine, getting free traffic is much more difficult than paying for visitors. Getting on the first page of Google search results for your chosen website keywords is your driving motivator.
You should focus on the following techniques for your main SEO strategy:
On Page SEO - Optimize your on-page content to reflect your carefully chosen keywords
Titles, headers, keyword density, tags, quality outbound links, etc...
Off Page SEO - Link building (One way link building in particular)
An extremely important aspect in search engine optimization is link building. One way link building is the best link building method and should be your top priority. This is where your website link appears on someone else's site. Google likes to see links to your website from various other relevant sites. All sites are not created equal however. Not only does Google like to see sites linking back to your site, but those websites must also be relevant and authoritative sites. One backlink from a reputable and popular site is worth more than one hundred backlinks from shady lesser known sites.
This is included :
Article marketing
Social networking and social bookmarking
Blog commenting and forum posting
Directory submisions, etc...
Hope this helpful