Hi, Unkonoir! Thanks for posting your artwork.
First of all I want to say that I like your use of color, there's some ambitious ideas in terms of color swatches that you're blending together, it makes the eye follow the shapes well. However I think what would be helpful at this point is to go back a little bit to construction and think about 'the joy of pixels' a bit less and how to best represent volumes and light and texture a bit more. What I mean by this is that I feel you've started with relatively simple pixel sketches and then you colored them in and had lots of fun (fun is good, it shows in your final artwork!) with colors and some dithering an detail work on the dragon horns for example, the hair strands and so on. But before you got to that, it would have served you much better to have spent a bit more time with the sketch itself. For the dragon for example, really nailing down that worm-like body as a series of volumes with foreshortening and so on would have helped you a lot to make it more clear to the viewer. Never be afraid of looking at references from real life. Google a few snakes or serpents for ideas you can take and simplify and apply to your artwork. At this point you're going from imagination, and there's limits to how you'll learn like this. Please don't be discouraged by this advice, I can see you've already got some talent going and you are having fun with your pixels, but a bit more construction will really boost your work at this point.
The second piece I like more, probably because you stuck to your reference a bit more? Still I am not 100% as to how the face works. I love the pixel clusters on the legs, the tunic and the cape, though, you've got some good instincts about how to make your pixels work together there, but I think the helmet could use a little bit of a disambiguation. Would you like to share the reference so I can see what you were going for, there?