A huge question....
Firstly you need to discover if your search terms are even being used its no point wasting a month trying to rank for fresh dairy if your clients are looking for fresh milk. You can use google adwords tool, Traffic Travis or Market Samurai to begin exploring those options.

Then you need to discover if your choice of keyword is a field one can compete in. A great example would be trying to rank for website SEO it can be done but its going to be expensive and likely extremely hard. Now if your trying to sell SEO in your city or town, website seo in NewDelhi. That may be more achievable and even more profitable.

Then to begin ranking for those terms, take a long hard look at your one page markup, this included titles, heading, metatags,content tags and page description. Most vitally solid original content relevant to your search terms. In a perfect world your content will be so amazing people will link to it and your site will soar up the rankings. In reality most of us have to look for search terms that convert well but are not as competitive as say generic terms like "quality silk shirt".

Hopefully this will give you some information to research and enable you to come back with more questions.