Hey there, welcome to Pixelation!
A few quick comments:
- The source sheet has a lot of noise, maybe you saved it as a .jpg at some point. Try to upload only .png or .gif images without any such noise, and preferably at normal scale (1x1 pixel size, instead of 2x2 or 3x3) to make it easier for people to make changes.
- Right now you have mixed pixel scales, which means that it looks like this is a 3x scale, but you've actually got some places that are 1X. Mixing scales rarely looks good in my eyes. In this particular case, I don't see the point of it.
- When walking, it looks like his legs remain still above the knee, and he's just moving everything below the knee. It's strange. I would make it look like he's raising his thighs and knees with every step forward.
- I know this is stylized, but I think his head could use a bit of work, because the hair implies that we're seeing him from the side, but the eyes imply that we're seeing him from the front.
- I'm not a huge fan of the colours. His sweater is blue and purple-ish, his pants are teal and his head kind of orange. Those three colours don't mix particularly well in my eyes. Maybe you should consider more classic combination of colours. It may feel unoriginal, but standard colour combinations are standard for a reason
- When picking different colours to create depth, highlights and shadows, try to experiment with different hues and different saturation. So instead of making his hair two nearly identical colours with roughly the same hue (color) and saturation, you could try using two different colours, like orange and brown. If you look at good pixel art, you'll notice it often uses many different colours in combination like that.
