Note: If you can’t justify using Ahrefs on a monthly basis, you could sign up for a month, do your KW research and cancel. That said, if you can justify the monthly pricing it’s well worth keeping because you’ll get access to the ongoing functionality such as rank tracking and web monitoring. It also means there’s no need to use any other tools to track rankings or monitor mentions on the web.
One of the most important aspects of an effective SEO strategy is the ability to research, analyze, and ultimately select the keywords that are most likely to result in success for your clients. There are a variety of free tools available on the web specifically designed to help online marketers do just this. Each tool has its own unique methodology for collecting and presenting this data. Comparing any of the tools’ results without knowing the subtle differences can lead to incorrect inferences and an SEO strategy based on misinformation.
We prefer and suggest Long Tail Pro to all our clients. Long Tail Pro is the best long tail keyword research software online. I use their software for researching keywords for everything from social media marketing bios, to page and blog post titles, to headings (H2, H3, etc.), to meta descriptions, to YouTube descriptions, to content/articles, and so much more!
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?
What are you waiting for? Today is the first day of the rest of your internet marketing life. Yesterday would have been a better day to get Long Tail Pro. Tomorrow might be okay too. But today is even better. I’m telling you – when I first got my copy of Long Tail Pro – I was like a kid at Christmas time. It was SO much fun opening up new possibilities that I didn’t have without Long Tail Pro.
Analyze Keyword Difficulty – Targeting difficult keywords with the highest competition is not always the best idea. The SEMrush Keyword Difficulty tool helps you determine keywords’ difficulties. By indicating a particular keyword’s percentage of difficulty, this tool helps you estimate how easy it would be to seize your competitors’ organic positions in the SERPs.
Google Webmaster SEO Starter Guide - Originally written for Google Employees to improve website performance with users and search engines. Related Terms: SERP - Search Engine Rank Position  |  PageRank (PR) - Named for Google Co-founder, Larry Page. The PR Scale of 0-10 rates a web page. In the past, rank was based on the number of high ranking links pointing to the website. Recently factors like relevance and quality have gained importance. This website's current PR rating: 

Because great content requires a deep understanding of the main idea (e.g., “ac repair houston”) and the supporting subtopics that require coverage (e.g., “central ac vs portable ac systems”) and the common issues that users seek answers for (e.g., “freon,” “refrigeration loops,” “coolant refills,” “troubleshooting”), the effectiveness of a keyword reporting tool is only as strong as the SEO pro using it.
To be convinced of the effectiveness of the product, you have to watch the video. The major benefit you are going to derive from the product is the multiple seed keywords it delivers. Unlike other similar products that give only single seed keyword, you would get multiple seed keyword with this program and you can get this at a time. Because you can process more than one seed at one time, it saves you a lot of time and resources. This is a huge plus to this product.
TIP: A really good strategy for increasing your search engine rankings (and maybe even getting a featured snippet), is to pick a number of popular questions, and answer them in your content. You can do this in the form of a ‘Question & Answer’ section or maybe ‘FAQs’. Just pick half a dozen or so questions, and list them, together with a short answer.
Once you've entered a keyword, you'll be presented with a range of data: Google Search Volume, Competition, CPC, and Opportunity Score. This data provides advertisers with at-a-glance data that they can use as the basis for their next campaign. No other free keyword tool provides as much free keyword data as WordStream's new and improved Free Keyword Tool. Try it today and see how much easier keyword research can be with WordStream.

As a new customer trying to evaluate the software, I asked if my trial period could be extended once this fundamental issue was fixed, on the basis I couldn’t actually evaluate its requirements against my criteria. I was told this was not possible, which frankly, is very poor customer service. What’s the point of offering a trial period when customers are unable to fully test the software?

Long Tail Pro helps to assess the strength of your competition and put you ahead of your competitors. It would help you to rank higher than your competitors. When it fetches the keywords for you, it filters it and delivers the relevant ones after filtering them and making them relevant to your domain. This way it would help place your business and your website ahead of its competitors.
Joost developed his own keyword research tool to come up with keywords as well! Yoast Suggests uses the Google Suggest functionality you know from searching in Google. It finds the keyword expansions Google gives and then requests more of them. So if you type ‘example‘, it’ll also give you the expansions for ‘example a…’ till ‘example z…’ etc. Just go on and try it and fill out some of your potential keywords. It’s a great way to quickly find more long tail keywords you can focus on.
I love Moz’s interface and how they give you data on the keywords. It’s easy-to-read, making it an ideal solution for both experts and newbies alike. They’ll show you both numeric and visual representations of a keyword’s monthly search volume, its opportunity for ranking, priority, and difficulty. They’ll also show you keyword suggestions and SERP analysis, which is fantastic and detailed.
To be able to rank in the search engines is an art that must be understood and finding the right Keyword tool that fits into your comfort zone is a must. What I mean by ‘comfort zone’ is having a keyword tool that doesn’t confuse you before you begin even searching. Some go into far too much detail than is necessary. All you need really are good long tail ‘common sense’ keywords that other marketers may have missed.
Long Tail Pro is a keyword research tool that helps you quickly find low competition keywords for your website.  In particular, the tool is built for people doing SEO (search engine optimization) as opposed to people doing paid ads (Google Adwords PPC).  I'm sure there are some advertisers that use the tool for paid ad keyword research, but the tool was built for SEO keyword research.