What eventually affects the ranking and what does not?

Here are some more important factors that affect the ranking:

Using keywords in title tag
Using keywords inside the page
The keyword in the page URL
The keyword in heading tags (h1, h2, h3)
The keyword in domain name
Google PageRank
Using keywords in the link anchor (internal linking)
Using keywords in anchor links (by domain)
Number of backlinks
The quality of backlinks
Linking relevant pages
Domain age
Links age

These are factors that does not affect the ranking:
General CSS and CSS Design
W3 validation
Javascript
Flash
Quality of content
Quality of design
Navigation in pictures
Grammar
Sitemap
Robots.txt
RSS
SEO Tools
SEO Software
Of course there is more but these are most important!