Here is a basic answer;
Work done on the site:
- having the keywords in the correct places on the site
- having relevant, unique content on the site
- adding relevant, unique content on a regular basis
- having the navigation and other parts of the site friendly to google
Links to the site
- Links should be from relevant sites
- Links should be from quality sites
- Google uses the links to judge who thinks the site is important
- Links should include keywords and not “click here”