Bright Edge is an enterprise SEO tool with many keyword services:
https://www.brightedge.com/
OK Dork Link on Content Marketing:
Answer the public: Good free tool to suggest long tail keywords or topics to add to content:
https://answerthepublic.com
SEO Clarity - Another enterprise level SEO tool
Marie Haynes - SEO Consultant for penalties
Log file analysis to find out what google is doing on your site:
That is about it. The core of it is to make high quality trustworthy pages for users. 