As per request (thanks, singingrabbitskull!), I did a half-tutorial, half-sporadic notes on how I generally render basic expressions.
There’s already a lot of cool tutorials that exist on how to do expressions, so I tried to just look at a lot of really minor details that I’ve used but haven’t seen commonly passed down.
required disclaimer: this is just how I go about it, feel free to ignore bits, steal bits, do whatever you want with them. Hope this helps, and if you have any questions scream at my inbox!