Keyword research should be the very first item in your SEO projects. Its the most important element of any SEO campaign. SEO starts even before creating a new website, before registering a domain for it.
You need to understand the audience you are marketing too, you need to research from user prospective that what they are looking for in your industry. This is very basic marketing principal and its also applied to internet marketing. Once you had researched audience that you are working on, you will have to research keywords/keyphrases that they are looking for in SE in a routine.
Once keywords are researched, you move forward and put these keywords in your overall SEO strategy. On page placement and use of keywords in your off page factors (link anchor text). You also do data mining, industry analysis to recognize your competition. This helps you in building an SEO strategy plus recognizing how your competition is achieving top rankings.
You can do keyword research using a keyword research tool. You can get keyword ideas through these tools, keyword search estimate and do competition analysis.
There are many keyword research tools in market, some are free while some are paid. They have different set of features and have different advantages. So its a good idea to use a combination of keyword research tools.
Google Adwords Tool: Google Adwords is the best free tool available. It provides you very good keyword ideas, similar keywords and number of searches performed monthly.
Free Wordtracker Tool: Its a limited version of WordTracker. You can do a quick search and get some ideas using this tool.
SEO Book Keyword Tool: This is a good tool, provides daily estimate of searches performed.
Lately I’m relying on Google Adwords tool as Google started sharing number of searches this year. Next I’d planned to write a post on ‘How to do competition analysis’ after finding your main keywords. Please bookmark to stay updated.