I'm really struggling with figuring out mirror heads!! How do you draw them? Do got tips? (Luv Rin. Rin is good. Will doddle one day)
Sure! I am Not Great at tutorial stuff but this is pretty much how I handle heads, I hope this makes sense ;O;
I prefer to work out a simple base shape before anything - in Rin’s case her head is kind of teardrop-shaped.

So from the top she’s pretty much a teardrop, and from the side she looks like a pointy dog snake. Don’t forget the pivot point where the jaw opens, that will help you a lot with expressions and structure:

I still struggle with angles and 3D-ness in general, but that stuff always gets better with practice.
If I want to get a bit more detailed and snarly then I still work from that basic teardrop head, sort of carving away at the mouth area. I think of the face as a wrapping around the skull. Pulling back the lips will scrunch up the face, and reveal more teeth and gum.

I tend to add horns/fins afterwards.
Oh and of course you can play with all kinds of face shapes :0

As always I’d suggest looking at animals for reference if you’re having trouble. Dogs, lizards, dinosaurs, whatever you’re feeling - skulls can be particularly useful to look at. :]
Hopefully that helps a bit!