In addition to this excellent post, I would like to submit my advice for inspecting the PKGBUILD files:
as well as this simple little script that just opens the web browser to the package page on aur.archlinux.org, so you can view the comments before installing:
#!/bin/bash
xdg-open >/dev/null 2>&1 "https://aur.archlinux.org/packages/$1/"
Save it to somewhere in the $PATH, name it, for example, aur and chmod u+x aur. When want to look at the aur webpage, just use aur package-name, for example:
aur minecraft-launcher
and it will open https://aur.archlinux.org/packages/minecraft-launcher/ in your browser, which is quite useful, in my opinion.