Wordstream is a free keyword tool that makes it easy and fast to get those keywords that your business needs most in order to drive traffic through paid and organic search.  All you need to do is enter a website URL or keyword and you will get hundreds of relevant keyword results that are tailored to your country or industry. Every keyword has an estimated CPC, competition score, and a proprietary opportunity score that will assist you in budgeting for your online campaigns. You can download your list in a CSV format and upload it in AdWords directly and begin to work on your new campaigns.

And so on and so on. The point of this step isn't to come up with your final list of keyword phrases -- you just want to end up with a brain dump of phrases you think potential customers might use to search for content related to that particular topic bucket. We'll narrow the lists down later in the process so you don't have something too unwieldy.
So whilst Long Tail Pro has just continued to grow in revenue every single year and comes highly recommended, you may want to check if all the important features are fully functioning before signing up. Especially the KC feature (keyword competitiveness) as it is so fundamental to keyword research and making an informed choice on whether or not to go into a particular niche.
When I finally made the decision the get Long Tail Pro way back in December of 2012 – I honestly had no idea how much this one piece of software would impact everything I do online. I knew that it would help me find more and better keywords right off the bat. But I didn’t know exactly how much it would positively affect my ability to actually make money online. I can say with confidence, that Long Tail Pro is the one tool that has made the biggest difference (by far), in my ability to get traffic to websites and actually earn money online.
It would be great if you can provide comparative analysis of this tool with Google Keyword Planner. Since you’re using this tool so you can provide best comparison. One differentiation which I understood is that this tool works for yahoo and bing as well whereas Google keyword planner works only for Google but Google being a dominating search engine, gives the highest returns, so only this reason may not be enough to buy it.