Google looks at 3 things:
1.) On page keyword density.
- Name images using keywords and use alt tags
- Use keywords in H1, H2, H3... etc. tags
- Do your keyword research and use them in your site.
2.) Backlinks. The more backlinks you have from related sites, the better
3.) Dynamic pages. The more often your site is updated, the more up-to-date and fresh the content appears to be.
Some other helpful factors... age of domain, permalinks with keywords, keywords in domain, validated pages, fast loading pages that use sprites instead of a million little images... etc.
That's it. The devil is in the details.