There is two things you have to keep in mind
A. On page optimization
B. off page optimization
On page optimization: keyword analysis using tools, competitor keyword analysis. Then you have utilized these analyzed key phrases in title, meta tags, headers, body and images. This helps in better positioning of your website for your optimized keywords.
Off page optimization: It helps in increasing the back links of a website and thus the page rank of the website. This process can be achieved in the following ways:
a. Link Directory submission
b. Article Submission
c. Press release submission
d. Social Bookmarking
e. Social Networking
f. Forum Posting
g. Blog commenting
h. Rss Directory submission