I am setting up an analytics cloud environment for my own use. What should I know about cloud security?

I know how to set up instances at AWS, and GC, and basically the only security measure I take is using IAM on AWS.

Since data is flow around a few instances, I should have more secure communication, I guess.

What are the best practices (which I am sure I am missing) for such use case?

(this is for learning purpose only, I wouldn't do it without the help of a capable professional at my own company, of course)