In order to announce your presence to the web and start to build your site's popularity, the single most important SEO strategy is building links to your site.
This can be accomplished in a number of ways;
Natural link building is what the search engines like. People see your site and like it or want to reference it because it's related to their site and they link to you voluntarily and in most cases, without even telling you. When you have great original content this happens frequently.
The problem is, how do other webmasters get to see your site? Most would find it in search engines but if you don't have any links to you, it's hard to get found in the searches so it creates a catch 22 situation.
Search engines don't like manipulated engine optimization like link trades and purchases but webmasters don't build sites so that no one will visit so most will resort to some form of manipulated backlinking strategy.
If you are going to go that route then one way to get reasonably good links is to look for directory with a good Page Rank Score with Google or a word cloud site such as Whos4you.com that offers very reasonable placement on a PR5 site. Your site is shown on the front page in an order based on your bid for the placement. But, even once your site has drifted off the front page, it's still visible on the past links page providing you a permanent backlink. A lot of bang for a little buck.
