Are you using masks to their full potential? Do you even know what masks are? If you answered no to either of those questions, get ready to have your mind blown. Masking is one of the most abstract concepts in Photoshop painting, but in my opinion it's the secret for truly efficient workflows. Though it doesn't feel like a traditional painter's process, it's a skill no digital painter should live without. This video focuses on painting textural overlays and the concept of 'nested masking' for maximum versatility.
If you're not familiar with masking, these are good videos to watch first: Masking 101 pt.1, Masking 101 pt. 2, Masking 101 pt. 3
If you want to experiment with the PSD file from the lesson, here is the robot for download.