I've used latex on and off over the years, I can write complicated math expressions off the top of my head pretty easily. For document formatting and package us

I've used latex on and off over the years, I can write complicated math expressions off the top of my head pretty easily. For document formatting and package use, however, I need to look up syntax and examples every time. Where can I learn the how all the messy syntax of latex (aside from the math notation itself) is supposed to work? Or should I just stop trying, because it's a lovecraftian tangle that will drive me insane?