Hope you don't mind but I did a little draw over on your assignment. I think you've got the major forms down but I noticed a few things that could help you out.
You have the bottom plane of the nose bulging out a bit to much. It's mostly flat with just a bit of a bulge.
With elf ears or any kind of pointed ear I've noticed that stretching out that "y" shape helps the ear look more believable. And some of your ears looked a bit flat. Try tracing over the different forms of the ear like with the anatomy in the first assignment. I've done that before to just really get a better idea of how the form turns and overlaps.
You've made a good start, keep at it!