You need to check all possible keywords and keyword combinations for relevance, popularity, competition and profitability. Since it may take forever to do that manually, you may seek help from some good keyword research tools.
I’ve been using Keyword Country with great success. It not just helps me to research profitable keywords (including misspellings, LSI, synonyms etc) but also lets me spy on my competitors’ SEO and PPC strategy. I am all for it!
There are many tools for researching keywords. But Google Adword keyword tool is easy to use & understand. It will help you to get competition, Global & local monthly searches for the keywords. So select the keywords on the basis of the good global & local monthly searches & with the low competition.
Google keyword tool is one of the effective, important and easy way to search and analyze your keywords. Keywords is the main thing in your website which help you get traffic and rank on search engine.