Pretty much everyone engaged in the ‘content wars’ have some level of focus on keywords.
It makes logical sense to include them in your headlines, and body copy where appropriate, and while ‘keyword stuffing’ now brings the wrath of Google down on you, being sensible still carries weight.
There are a number of paid keyword tools that do a great job, but a pretty good job can be done for free just by applying some thought and a bit of common sense.
Some of the ideas I have used in preparation of this blog are:
Google auto complete. Start typing a query into Google and it gives auto options. These are nothing more than Google scanning the similar terms put into search and returning their most common responses. Ie, a keyword or phrase.
Wikipedia. Thousands of experts collect and curate information on many topics. Any page that deals with your niche will have links and words that can be used as keywords, curated by experts.
Google related searches. Every first page of the search results give you a number of related searches at the bottom of the page. Often some good ideas are hidden in there.
Amazon. This may not be an obvious choice, but if you have a look inside a book in your niche, you will see the chapter headings. Somebody who presumably has a bit of knowledge in your niche has taken the trouble to write a book, and set out the important stuff in the chapter headings, might be an idea there?
Quora.com. Quora is a Q&A platform, for the uninitiated, so there are discussions on many topics, probably yours, so there are a range of words and phrases used that could give some ideas.
Forums. Type your topic + Forum into the search box and up will come the forums related to your search term. Again, these are discussions on the topic for which you are looking for keywords, so there are likely to be some good ideas floating around.
Google keyword planner. This is a great tool, suffering from success. It gives only specific variations on a word or phrase you type in, there are no similes or suggestions in there, no variations beyond the specific word or phrase you typed, no imagination or inference is applied. The obvious advantage is that you also get some data which can be very useful. On the flip side, everyone uses it, so finding a word that is different, but still relevant will not happen in this tool.
The paid tools are very good, but for a medium or small business, an expense that they often choose to avoid, as they can be expensive. No amount of keyword magic however can replace a creative and relevant strategy and Value Proposition executed with precision.