If you want details about optimizing, there are many factors and I'll throw them by most valued top 10 ranking factors in order as of this writing:

**1) Keyword use in Document title
2) Link Popularity of Website aka (backlinks)
3) Link Text of Inbound Links aka Anchor text
**4) Keyword use in Body Text
5) Age of Website (debateable)
**6) Keyword use in H1 Headline text
7) Keyword use in Domain name
8) Keyword use in Page URL
9) Links from Social Networks
10) Server Speed

**Densities make a huge difference and must be calculated correctly!

Bernard