You maybe want to look into something called key frames, tweens and onion skinning.

Animation can be tricky - there's a lot to keep in mind. It looks like you've tried to keep all your volumes as best you can, which is good. However if you really want to push it further then I'd suggest the character blinks during the middle of the turn and not at the end, while also dipping their head in a nice smooth arcing motion.Similar to what you see in this animation - https://www.youtube.com/watch?v=mZa5YW5FS10 Adding some contrast by having the head in a slightly different position and at the start and end of the movement will help too (instead of keeping it all in that sphere in the center).

I think you'll find that most head turns follow this dipping arc and blink pattern in animation, and even in life - albeit much more subtle. It's a good attempt though - you've gone for a pretty complex thing to start with - facial animation can be very difficult. Most people start with the bouncing ball or a floursack.