The real foundation of building and getting quality site are:

1.Rich and quality content: Content is the not the "King" but Quality Content is the "King". So build your website with rich, informative, interesting and Quality content.

2.Relevant and quality link exchanges: Links are very important for your website. So get relevant, justified and Quality link exchanges for your site. Put more effort on collecting links that 'defines' your site.

3.No adult content: Hmn, make sure that there are no Adult contents and links in your site. If you can make sure that, then you can get listed in the DMoz Directory and allow your site a have a fair chance in getting good Search Engine Rankings. So, this is a very important aspect for building a quality site.

4.No spam, no scam and virus in the content of the site: Also make sure that there is no Virus in the site's content. No Spamming or Scams should be entertained while promoting your site's products.

5. Keywords: Put more and more keywords in the content of you site. Avoid Duplicate Content because the search engines may get your site backlisted in the Supplemental Database.

Some related links:

Quality content
What is Good content site?
Essentials for a ideal website