IMO the best way to learn how to draw muscles is to learn basic anatomy. Though if you're drawing some exotic creature, you can draw muscles structure, based on some common animal, like lizard or tiger, for example. If anatomy is very boring for you, then look at some fantasy pictures, there are a lot of them in Internet. IMO the main things here are: what each muscle do, where it attached to joints, and it's size.

Ah yes. At first I was quite proud of this piece of art, but after about a week I began to see what you mean. The shading is quite weak, and this is because back then I did not know how to properly shade scales while still communicating depth with them. I can also agree with you on the muscles, and as for me, muscles are my one big weakness...do you have any suggestions on how I could learn to draw them properly? And as for the size, I'm used to it because it feels natural for me. It's 256x224, the resolution of the NES/SNES, and it's like...my golden ratio of art. I always use either that image size, or a multiple of it for all of my art. I do think I've improved at least a little bit in my shading, though, with my newer piece "Platino Moe" Thanks for the crit!

I like youк daring to work with such a big pictures.  You're not affraid them as me for example.Well, due to your realism practice I have couple of things to say. And they are all about shading (there will be a lot of this word below ). The picture looks too flat, there's no volume in it. It's because of poor shading that doesn't work here. I mean you shade only the edges of bodyparts, though these same bodyparts make shadows too. The dragon have muscles, and shading can help to show them (there's not only realism reason here, your character will look stronger and powerfull too). Those very nice scales (I really like this texture you made) looks flat, because the whole body have no proper lighting, the same thing about wings (they are almost lost in all this mostly identical grey tones). So, have a try to master some basic shading and refine this image, you have a lot of energy and creativity.