I love drawing hair (and colouring it).
All the characters in my webcomics have pretty boring hair, though :/
I also like drawing hands with visible fingernails (although I suck at drawing hands).
Oh, and eyepatches!
There was a time when I was about ten and I only drew dragons, reptiles and dinosaurs...I even got books about dinosaurs and reptiles to learn reptilian anatomy better. But I abruptly stopped at some point and now I have that feeling that all my previous training is all lost at this point...
Eyes. Also, horses. This includes zombie unicorns. I also draw random demonic things without any ideas or sketches. Just a thing with several eyes, maybe, wings, very long tails, and extremely long teeth