I hope you gained some good ideas from this peek at my process!
My Halloween costume this year was a dragon, inspired by Ysera in World of Warcraft. I created all the costume pieces, including the prosthetics. This project definitely consumed all my free time for the past 3 months and it took about 6 hours to get myself ready when I wore it. But it was all worth it just so I could be a dragon!
I start all my costumes with reference images and sketching. I took most of my inspiration from Ysera, a dragon in World of Warcraft. I highly recommend doing a quick sketch, even if you think you're bad at drawing. It's amazing how much it helps as a reference while you work.