Also if you want critque here it is. Work on first his head. You got the jaw line shape wrong, also his lower jaw is very thin. Also erase the lines, it makes it look more professional. Plus be aware that his eye brows are not brows like a human and rather muscles, which are usually only visible when he is angry. If you want a happy expression erase the eyebrows and nose lines. Also replace the nose with two nose slits, as from a front view his nose is not prominent. Remember his nose almost blends with his head, so its rather two slits then a human or cat like nose. Another thing, Toothless is not blue; he is black. But when coloring with black you often need to shade and highlight using different shades of black and gray. Lastly, his ear nubs in the movie are different sizes and shapes. Take a look at a picture; the outer two are never in the same position, and the middle two are different shapes and sizes from the other.



Good luck! And as the other user says; practice makes perfect!