If I want to bring  a particular keyword on google first page what activities i have to performed

Post Blogging with the quality content and additionally do the following
Forum posting
Blog commenting
SMO
Guest blogging

Keyword ranking can be achieved by good on page and off page seo techniques. Some of the good off page techniques to rank keywords are:

Guest posting
Article submission
Press release submission
Social bookmarks
Classified ads
Infographics submission