Rigging from reference/Having natural deformations/creating complex rigs?

Because I’ve been still learning sculpting and retopology and it’s been taking a bit, I wanted to still learn how to rig for once I’m able to make full characters. My end goal is to be able to rig a character to fit a pose from reference or imagination, but the first problem I had for my firsts rigs was that my character deformed like a balloon animal. This was my first reference: https://imgur.com/a/ZGniOsa, I didn’t even move the arm to go to the back of the head because… This would happen: https://imgur.com/a/unrPojb How do I make this stop? Even weight painting doesn’t seem to save this, I don’t think I’m doing it properly though. What’s the right way to do this?

Okay first of all nice character model. There could be two thing (possibly be more) it could be simply the model because i remember hearing you have to design them a certain way.
Or it could be the way you designed your rigg but its probably a mixture of that and weight painting.
I’m not a professional but probably focus on the rigg and weight paint. Sorry if this didn’t help in any way.

Might help to put in a blend. You can post one here and then post the URL you get. http://pasteall.org/blend/ Did you design your model with topology for animation in mind? Have you rigged your bones with the correct bone rolls? Have you weight painted correctly? What version of Blender are you using?