I was linked to these two videos by Jim Weirich when I started working with Ruby and Rails again by my friend/colleague/boss and they really helped get into the mindset of working with Ruby in a good, SOLID OOP way. They also gave me a path to not use Rails magic too often, and to decouple logic and classes from the framework as much as possible.

Advanced Ruby Class Design by Jim Weirich

Decoupling Ruby from Rails by Jim Weirich