Heads. This is where I had another 'I can't draw faces at all' moment and spent several days studying them. A lot of people said they actually liked these though, so I might be on the right track with them for once.
A lot of this practice was also done utilizing a 3D model as a guideline to help me sanity check my proportions and perspective. Check it out: https://www.artstation.com/artwork/6a0Par