If you don't know what to read this evening and you're interested in how to create proper docker images, then read Dockerfile best practices:
Writing production-worthy Dockerfiles is, unfortunately, not as simple as you would imagine. Most Docker images in the wild fail here, and even professionals often get this wrong.
This repository has best-practices for writing Dockerfiles that I (@slimsag) have quite painfully learned over the years both from my personal projects and from my work @sourcegraph. This is all guidance, not a mandate - there may sometimes be reasons to not do what is described here, but if you don't know then this is probably what you should be doing.
It shows you a basic Dockerfile which you can tinker for your own projects, based on all their best-practices. No more excuses to do it in a different manner.