There are probably more than 100 rules that Google uses to rank pages in the search engine result pages (SERP). No one really knows all the rules, and they're changing on a periodic basis. Various confirmed and suspected SEO rules described here are educated guesses by SEO experts.

Positive Google Rules (On Page)

1. Keyword in URL.
2. Keyword in domain name.
3. Keyword in title tag.
4. Keyword in Heading tag (i.e. H1, H2, and H3).

Positive Google Rules (Off Page)

1. Google Page Rank (Higher the better).
2. Anchor text of inbound link to your site.
3. Link from "Expert" site.
4. In directories (dmoz.org, Yahoo, and etc.)
5. Site Age.

Negative Google Rules (On Page)

1. No body text. Text represented in graphics form.
2. Over Optimization Penalty (OOP) - Google Florida
3. Link to a bad link farm.
4. Redirect through refresh metatags.
5. Use of poison words.
6. Excessive cross-linking within same IP block.
7. Keyword Stuffing in body, meta tags, and alt text.

Negative Google Rules (Off Page)

1. Zero Links to your site.
2. Link buying.
3. Cloaking
4. Domain Hijacking (Copied website)
5. Rank Manipulation by Competitor Attack.

For a comprehensive details of this report, please visit Google Ranking Factors