"Our whole team has a copy of Keyword Researcher, we use it for everyone of our client's keyword research for the 'Long Tail' and we use it every day to come up with blog post ideas and ideas for guest posting. We couldn't live without this tool. I have used every paid keyword research tool under the sun, and this by far is my favorite tool for mining the Long Tail."
The simplest KW research tool is google. Type in your topic and scroll to the bottom to see what related results show up. Use those to either write an article or to supplement other articles with some of the keywords. Yes, they are primary phrases so you may not rank for them right away but building your site with these in it will help get rank for them eventually. Also look at what other articles that show up for the keyword use.
The cost is only a one time payment…no monthly fees, which is fantastic if you’re on a budget, and you get lifetime updates and some truly excellent training videos as well as some very useful built-in tools. I’ve also tried other paid keyword tools such as Market Samurai, Wordtracker, Jaaxy, and others, and let me tell you this….none of them come close to Keyword Researcher Pro for value and ease of use.
3) Google: This is pretty straight forward but it’s the main reason I like it. I search for my main seed keyword in Google, and use the keywords that Google itself highlights in bold on the search results, plus the “Searches related to” section at the bottom to get keyword variations or LSI. That’s basically what Google is telling you that topic is about. No need for a thousands other tools. I use these to optimize the on page of my target pages as well.