I cannot vouch for any of this (just getting started with PW myself), but those are some links that I saved for future studying: https://www.pwtuts.com/ https://webdesign.tutsplus.com/categories/processwire https://mauricius.dev/tags/#processwire https://processwire.dev/ https://web.archive.org/web/20170816032544/https://abdus.co/blog/creating-a-simple-and-configurable-module-for-processwire/
Edit:
Removed link to processwire-recipes(dot)com, as the website now links to an unsafe (adware / scareware) website...
