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.
The “Starter” tier, with 1000 keyword lookups every 24 hours should be enough for anyone starting out in blogging – or even people who are quite established. It’s pleasing to see a product where they don’t seem to trick you into having to pay for a more expensive version. On the more negative side, I did feel that you’re nudged towards doing annual payment, with the monthly option kept slightly “hidden.”
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.

3. Finally, there's just good old research through trends and news. Google Trends, keeping up on industry news of the business, and even newsjacking (if there are relevant topics). These all require different resources depending on the business, but once you find the leaders in their news you can not only leverage them for keyword research but also glean insights into how you can become an industry leader yourself (and dominate SEO).
"This tool is simply Amazing. I've been uncovering literally thousands of highly related keywords for my clients websites, with this tool new content ideas have become a breeze. I literally have hundreds of new ideas for articles to write about for my sites and my clients sites. The Keyword Researcher tool was truly a great buy for my business and I highly recommend it to anyone."

5. Use the Keyword Competitiveness “Fetch Now” feature. Now that your list is trimmed down after you applied all those filters in the previous step, you use the KC “Fetch Now” feature that saves you time in retrieving all that invaluable information. Again, depending on the number of keywords it has to check it make take a while (remember that LTP needs to retrieve information from several sources including Google and Moz). During this bulk check if LTP prompts with Google captchas to fill out, just close the software and wait 10 minutes to reopen it and continue your work. (This issue should have already been fixed now with the latest updates to the tool.)

This keyword research tool is effective, automatically providing you with keyword suggestions that other sites haven’t necessarily turned up (which it’s intended to do), along with their search volume, CPC, and Adwords competition. In order to get any actual information about the keywords, though, you need to upgrade to Keyword Tool Pro (which is a little misleading on the site copy). This plan is $88 a month, and if you’re just doing keyword research for Google, I’d recommend choosing one of the other tools for the price.
This is one of the best articles on Keyword research tool that I have encountered. However, To add more to this, I just wanna point out a tool (LSI Graph) for an outstanding long tail & semantic keyword research. After the recent Google algorithm, Google is now, however focussing more on context & semantics than keyword alone. What do you think about it?
Making a list remains hard. And up until a few years ago, doing your keyword research was much easier. You could simply check Google Analytics to see which terms people used to find your website. That is no longer possible. So you’re pretty much left in the dark about the terms people use in search engines to end up at your website. Luckily, there are some other tools which can make your keyword research a bit easier, and could help you speed up the process a bit:
If you already create niche websites, you can clearly see how everything I’ve discussed above will benefit you. In fact, you probably already understood all of it. But maybe you are a blogger who has never thought of creating a niche website. Is this you? Let me tell you – if you can create a blog, you can create a niche website. It is not hard at all to create a small site, laser focused on a very specific topic, that will earn at least enough to make Long Tail Pro pay for itself.
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.