I might as well recommend something that I wrote. This is a short article in the Amstat News, a monthly newsletter of the American Statistical Association. I talk about all the reasons you wouldn’t want to be an independent consultant and the one big reason why you would–being in control.
Simon S, Why be an independent consultant? Amstat News 2017 (April). Available at http://magazine.amstat.org/blog/2017/04/01/whyconsult/.
You can find an earlier version of this page on my blog.