One way of doing keyword research is the use of Google suggest. When you type a word into the Google search box, it will automatically drop down a short list of other phrases related to the word you typed in.
But Google suggest shows only a few terms. But there is this free tool called Suggester where you can get a bigger list of related terms.
Here is the link to Suggester: http://suggester.promediacorp.com/
Then there is another free keyword suggestion tool called Übersuggest; which gets its keywords from both Google Suggest and other suggest services.
Here is the link to Übersuggest: http://ubersuggest.org/
