This may not be 3d or "game art" related but at my school one of my teachers gives life drawing courses on monday. I love going to them to practise my traditional art skills because I think I need to master those as my fundamentals and that will eventually help me be a better artist even in the game industry.
I have been doing this now for a couple of classes and I really think it helps and gives me an opportunity to forcefully try something different. Our teacher sends us tutorials or just videos on painting and since every artist uses different approaches to painting, I every week want to try something new. For the past couple of weeks I've started using oilpaints and LOVE IT. I've only recently tried colors but so far its fun and super interesting.