So first we'll cover anatomy.

The head is too big for the body, so I sketched out proportions. The head should never, ever be bigger than the shoulders.

Also I decked out the ears for one of them seemed too close to the center. But, I'll admit to making this mistake sow times too.

The neck is quite thick for the body, you need to thin it out a bit but not too much.

Men tend to have thicker, more stubbier necks while women have thin, even long necks.

Even out the eyes a bit.

That's about all I got.