Your facial expressions and style is very clean and easy to understand. I can see that you dont use aliasing on your lines as they look a bit sharp and pixelated. I would recommend using a software like Krita (free) and enable even some slight aliasing to smooth out the lines, and to make your images on larger canvases to make help the smoothing even more. Keep on refining your style and consider playing with shading more to make your art pop out more. Good work! [Edit after response] ah ok that's cool then. In that case a larger canvas size would help it look even sharper.