The Drawing is a great start for Dragons! I'm not sure what the original you copied from looked like so I'm working based on what I can see. and you can do this yourself on your next drawing as well, but Imagine the dragon in a 3D space, and pick up a cube. if you can see the bottom of the cube the top is hidden and if you can see the top than the bottom is hidden. I've highlighted in your drawing which side is most visible (the bottom) which means when I look at the eye, it feels strange to see the opposite one higher or at all. The line (highlighted in blue) is what gives the biggest impression of seeing the top of the head, because it outlines a flat side. if you erase it than the top will loose its implied flat plane, you could do curves like on the neck instead to see how it changes. other than that, have fun drawing more dragons and you will soon pick up these little things.