Effective keyword research method is to get the list of keywords through different and reliable keyword research tools and then apply your logic, experience and context requirement. This will give you the best list of keywords.
If you have a tool like Scrapebox, you can scrape all of Google’s auto suggest keywords. This can be especially useful if you are using content marketing as a strategy because it can throw up some decent ideas for writing content.
Following are some method for keyword research
1. Make a list of basic keywords and then use various keyword research tools to find out relevant keywords
2. Check competitors keywords
3. Think from visitor’s point of view what he or she will search if he need particular thing
4. Ultimately use your experience and intelligence to shortlist final keywords.
Apart from this we can look at Google Analytic to get some insight as to what keywords people are using to arrive at your site. Although there source is not as plentiful as it used to be, is still can provide good insight.
Another good 3rd party tool is Ubersuggest at ubersuggest.org. If you already have an adwords account running, a great report to run is the Search Query Report to see what the actual queries people are typing in to trigger your ads and arrive at your site.