I get asked about edges a lot and thought I'd share a quick cheatsheet of where to put hard+soft shadows. It's the quickest way to add some dimension to your drawing imo!
1st GIF: The easiest way imo is to put down a your shadows first, and then go over them with a soft eraser. That way, you avoid confusing yourself or overcomplicating things..
2nd GIF: A lifesaviour - a brush with hard and soft edges! I'll include the brush in the attachments!
I'm planning on making more "quick tips"-types of things like this (maybe bi-monthly?), so if there's anything you'd like to see specifically, I'll be more than happy to go over them!