How can I become proficient in LaTeX?

Don't just read. Start writing and then google whatever you need.

It's unlikely that there will be a problem that hasn't been already been addressed.

Welcome to TeX!

I would recommend to make a free account at Overleaf (https://www.overleaf.com/) and start practicing. Overleaf is easy to use for beginners, and it has a great tutorial. For example, as you mentioned TikZ, here is a good link: https://www.overleaf.com/learn/latex/TikZ_package

Start running examples and play by changing the code to develop an understanding of the implementation. Feel free to post a new question when you get stuck on a specific problem. This community is very helpful.

Another resource I would recommend is https://texample.net/. It has a lot of examples that you can just paste in Overleaf, run and play around to develop intuition and gain expertise. For TikZ, see https://texample.net/tikz/examples/

Best of luck!