Start whit a skech of the head whit simple shapes.
Start drawing the head. Make the mouth and the place where the horns will start from.
Continue whit making the horn, the neck and make a few lines aroun the end of the mouth, around the eyes and the nose.
Add more details if you want. I choose to make a mane. Color it if you like, or don't, but eader you choose make some shadows arownd the lines we added in step 3 for better look of the dragon. Well the tut is about a simple head, so this is the final :).