Frontend client technologies, tools, and best practices

I'm new to web development and wanted some advice to understand what I should be doing to write a front end client. I've been searching around for technologies, but there is just so much to consume and digest that I don't really know where to start. My first project was to create a simple flask application that served static web pages with a couple of ajax calls. It sufficed for a first time project, but it lacked best practices and front-end frameworks and libraries.

For my second project (which makes calls to my API), I want to incorporate best practices and a solid architecture. I want to start off by using React for the view. From what I understand I should have a package manager as well. There are lots of other technologies, but I'm having a little trouble trying to connect them all. Any advice?