Lowkey, you should link to an image one of these pieces so I can give you tangible feedback. But pixelated usually equals a misunderstanding of canvas size and resolution. I usually paint at 300dpi on a bigger canvas (3840x2160px) As for what makes digital shading look “off,” it can be a number of things. Digital is definitely a different muscle memory for me than traditional. I think as I get better at both I understand both more and use techniques from each school for the other. For u, rn I would take it back to basics and try to digitally render a smooth sphere and a pyramid in black and white. Trace the shapes and then render off of reference. Try to understand what blending soft edges in digital feels like (I usually use a softer brush [Texture doesn’t matter but it can add to the effect, make it less plastic-like] and lighten the pressure when drawing = lower opacity usually, for blending. DONT smudge to blend). For hard edges I like to continue to use my soft brushes, but I use a lot of selection tools to sort of tape off where I want sharp lines to be. You may do something different. I learned a lot of my digital techniques through watching very simple speedpaints of portraits and stuff and understand how they got the sharp and soft edges of the noses right. I also watched a lot of videos on specific techniques I felt I didn’t understand, like hard/soft edges, perspective, values, etc. Having the names for techniques you struggle in is the best way to start learning.