Some times it happens that you cannot think of any keywords for your SEO campaign. In such times you can put in bits and pieces of keywords and let the algorithm do its work. Such tools are called as keyword suggestion tools. I am not a core SEO hence i use free versions of Uber suggest and freekeywords.wordtracker.com/searches. Finalize on the keywords and then use keyword planner to get the estimated no of searches in Google keyword planner(which in my opinion is not very much useful)
'Keyword Country' is best for me among the other tools I’ve had a play around till now. Unlike other paid keyword research tools that pull and produce data directly from Google, KC generates a clean list of groups and keywords that you can directly use to create better content pages. It offers a free trial, you can bail out whenever you wish to
There is a tool named keyword planner a best tool to search the new keyword and work upon it is easy to find keyword Sugesstion here and also we can check competition over the keyword easily.
I think the newest Adsense Keyword Scraper is better than the old Research Tool..You can filter a little bit more now and they group things pretty nicely.
as everyone said, Google keyword planner is best , apart from this giant you may go for, 1) Longtailpro - Finding Long tail keywords 2) Ubersuggest.org - Find Long tail keywords which are already indexed in search engines These three are perfect and it is enough
You can check the following some good keyword research tools but don't forget to use google keyword planner tool. wordstream wordtracker keyworddiscovery spyfu