What are some things that one has to be ready with before starting a side project?

I am currently building a simple readme generator website as one of my personal projects. By almost at the end of the project, I realized I could have done some testing before every component is coded. And also realized I could have automated some workflows.

Sometimes I feel they are unnecessary and are just a waste of time if the project is small. But at the same time, these are some of the most underrated skills of a professional developer.

Anyways, what are your thoughts on this? And what are some things that a developer has to keep note of before or during the building of the side project?