Remember: when we speak for SEO, we don’t speak only for SEO. No matter how optimized your page is – if the page is not popular, you are out. Probably the most important thing, these days, is how many sites link to your page. And not only the number, but the quality plays a role. If many other, trusted sites included your page in their pages, you are popular. If you are the most popular in your keywords niche, even if the rest are better optimized, you’ll get the top-ranking. That’s the way Google answered to spammers, trying to over-optimize their pages for particular search term.
A large part of SEO is the effort spent obtaining links from other relevant web sites. This can be very time consuming, and frustrating as well. However, it's the number of incoming links that Google uses to assign PageRank. The higher your PageRank, the easier it is to get to the first page for your phrase. There are lots of spammy sites out there claiming to increase your link popularity with the click of a button. These are 99.99% useless, and probably won't get your site listed anywhere that will actually boost your ranking. This is a non-organic form of "seo", but is frowned upon in the community. Your results will be much better if you hand pick the sites you want to do a link exchange with.
The best place to start is to submit your url to all the directories in our “Submitting Your Web Site” section. These are free, and can help boost your PageRank once approved. It is not a wise idea to spam your URL into submission forms, this is typically what those "Submit Your Site to Over 20,000 Search Engines for $79.99" scams do. It would be surprising if even .01% actually were included in any directory that could actually help you.
Biz Directory Script is a web app that facilitates construction of a site of inbound links. Connectedy (http://www.connectedy.com) is an online service for establishing online link lists. Both tools allow grouping of links into pages by category.
There are some great directories out there which are free of charge. Some examples:
Blogs are another group of people which are more likely to link to your site, as long as it's relevant and provides some value to their visitors. You can typically do a search to find blogs, for example if your site is about grey whales, you could try searching Google for "Grey Whale Blog", and then email the owner of that blog. Also note the links that the blogger also has linked to, and try emailing those people. Often starting with a blog search is the best way to find relevant sites that may be willing to link to yours.
Taking the "grey whale" example, you may also try searching for your phrase in a search engine, and find the top 10 sites or so, then find out who links to those top 10 sites for "grey whale" and ask them to link to your Grey Whale site. You can find out which pages link to a site by typing "link:www.domain.com" in Google. See “Tracking Your Success” for more search tricks.
The final step is to actual write a customized email to the site author. Try to tailor each email so the owner feels you actually visited your site. A mass emailing containing, the words "Please link to www.domain.com" is surely going to end up in the trash box.
Try to include how your found their site, their url on which you want a link, and a brief sentence about your site. Then, tell them the url, and the text you want used in the link (this is very important - use your keyword phrase you are targeting here).
Something to this effect, short and sweet, and personalized. It takes time, but you'll have a better chance of not having your email deleted without a consideration.