Eat3d has a joint-based facial rigging tutorial that I've found to be pretty helpful - http://eat3d.com/facialrig Some of the material is getting pretty dated but for what I need to get done right now, I'm learning a lot from it.
can't go wrong with this, it's a classic and a very good intro to the topic: [ame="https://www.amazon.co.uk/Stop-Staring-Facial-Modeling-Animation/dp/0470609907/ref=dp_ob_title_bk"]Stop Staring: Facial Modeling and Animation Done Right: Amazon.co.uk: Jason Osipa: 9780470609903: Books[/ame]
I'm working on a faical rig myself. Since I want it to be pretty expressive, I've spent a fiaire bit of time on it. If your game engine supports it well, I would go for a couple of blendshapes (which is what I do) mixed with a few joints here and there for more control and flexibility. I've tried working wih joints but oh…