Very nice! Looks like my minions got an equally muscled brother :D
As a critique id say you could improve on the shadows, maybe take a reference (makes it so much easier) you put most of the shadows on the edges of armes or legs but this is rarely the case. The shadow is mostly the darkest close to the edges but not on the edges (there is light reflected from the bottom on the edges usually) hope I could help with that, it took me a while to figure that out...

Nice work! I like the blue and yellow contrast! For a beginner I'd give the tip for a next artwork to try and paint like a sculptor, through light and shaddow hard edges and soft edges you can make any object/caracter to look three dementional, you might wanna use reference for this since it's not easy to get all the shapes for shadows and light right. Also values are pretty important, getting a good contrast going on between lights and shadows :) thats what I just recently learned and now try to work with ^^ definitely got me some progress going ;) hope I could help

Love the expression of the dragon, all in all very cool!