Using the good ol' free Google Keyword Planner is great. But there is an alternate universe of Long Tail keyword phrases that live in Google's other database--namely, their "Autocomplete database." That's the database that is accessed when you're typing queries into the Google search box (notice that list of suggested keywords that pop up as you type?)
We at Moz custom-built the Keyword Explorer tool from the ground up to help streamline and improve how you discover and prioritize keywords. Keyword Explorer provides accurate monthly search volume data, an idea of how difficult it will be to rank for your keyword, estimated click-through rate, and a score representing your potential to rank. It also suggests related keywords for you to research. Because it cuts out a great deal of manual work and is free to try, we recommend starting there.

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.)
6. Filters. On the top area of the main pane, you can find the “Filters”. These will allow you to filter your keyword suggestions list in real time. Just start typing and your list will be filtered accordingly. You can filter for “Keywords” (to only show keywords that include a specific word or words); “Suggested Bid” & “Local Searches” allow you to enter minimum or maximum values; “Advertiser Competition” (this comes in handy, because the higher the competition the more money there is to be made if you target that keyword); “Avg. Amazon Reviews” (a neat feature for those who sell products on Amazon or have an Amazon FBA business — less reviews equal less competition, hence more chances to rank on top of Amazon’s product search pages); “Avg. Keyword Competitiveness” or “KC” is Long Tail Pro’s proprietary metric that calculates how hard it is to rank for a keyword in a range from 0 to 100 — 0 being no competition and 100 impossible to rank for. All of these filter columns can be used to sort the keyword suggestion list as you prefer.
You can receive keyword ideas from your audience or team because people are a rich source of keyword date. Seed keywords presents a unique tool that users utilize in generating keyword ideas from other individuals. You need to begin by creating a scenario in a question form by asking people what they would search for in case they are looking for answers to their questions. Seed keywords will develop a unique URL that you can share with your relevant audience or team once you have created a scenario. Your viewers will begin to enter their desired keyword phrases and this will be added to the seed keywords. This data is downloadable in the form of a CSV or you can simply click to view the results of each keyword in Google. You can look for the search volumes in other keyword tools like Google planner once you have your list of keywords.

"With Google giving over the home page to ads and their own properties for commercial keywords, the Long Tail keyword is more important than ever. If you have a website, you know that most of your traffic comes from keywords you never would have thought of. With Keyword Researcher, you can find them in advance and make sure that you're the one that snags this traffic. I use it for all of my e-commerce site planning."

SEMrush is a very useful tool for both researching competitors when starting a site or for growing an established site. I really like to find weaker niche sites that still seem to be ranking for lots of keywords; SEMrush helps me see what they are ranking for and what I can potentially target. You can also see what keywords you’re on the cusp of ranking for with your established site - another very useful feature.

Successful SEO requires multiple interrelated activities on all fronts: competition, keywords, link building, on-page and technical optimization. It creates a need for diverse tools, which is expensive. SEMrush solves this problem with an award-winning all-in-one toolkit that includes 17 tools covering all SEO fields. We’ll walk you through your SEO workflow, explaining how to get the most out of our toolkit.

I want to share how and why I sold the company in order to both educate and inspire potential software entrepreneurs.  I certainly don't know everything and obviously companies sell for much more than I sold Long Tail Pro for (I won't be featured in Tech Crunch anytime soon); however, I'm willing to share what I have learned and hopefully that can be beneficial to a few of you.