I drew it from life, no reference photo. I was surprised this one was even accepted. About those tutorials, those don't seem to work for me. I often have no idea what the author means, and have to do a lot of searching to grasp the concepts. It's frustrating, so I put it off.

It would be cool to have a reference photo (if you're looking for critique). In terms of pixelling technique, I think you'd be better off replacing the noise and random pixels on the glass with some simple structures or patterns. And if you're in the mood to look at tutorials again, this is a good piece to study banding and jaggies.