I am expanding the factors of on-page & off-page optimization that are mentioned in the original post that help a website to be noticed effectively by search engines.

On-page:
•If possible use domain name that reflect your business nature i.e. use targeted keywords like http://www.ukdomains.com

•Use hyphens (-) for long domains instead of underscores (_) i.e. http://www.uk-lowcost-domains.com & also use keywords in page names

•In Title Tag, 5 to 7 highly targeted keywords work well

•Use best suitable keywords in every page of your website, but avoid repetition and over use. Your page should not look like a search engine page, but it should be useful for visitors

•Remember! “Content is every thing”. Your content should be interesting and valuable by visitors.

•Use keywords in Headings, Alt Tags, Hyperlinks and file names

•Use Bullets & Text styles (bold, italic)

•Use search engine friendly navigation. It is highly recommended not to use JavaScript menus because search engines do not read them. Try to use DIV based or combination of CSS & JavaScript menus and put your relevant keywords in it.

•Try to avoid Flash based content in your website because search engines ignore Flash completely. Though, some Flash optimization techniques are implemented but at the end, search engines face problems while indexing.

Off-page techniques;

•Pay-per-Click advertising using Google AdWords, Yahoo! Search Marketing, and Microsoft adCenter.

•Participating in quality blogs, forums (with your signatures that contain your website address, email etc) & social networking sites

•Postings in famous groups like Yahoo, Google & MSN

•Participating in Yahoo Answers

•Banner/Link Exchange program
•Emailing promotional newsletters to targeted customers with your signatures (but avoid spamming)

•Posting free classified ads on quality sites