Thank you very much for your tips! its a big step forward! i made this one on an ipad with the Sketch club app, hence the scaling problems for i have no options to change the resolution. Thanks again.

Problems indeed. Just work at native resolution (1x, 100%), don't upscale or downscale for whatever reason. There is a zoom feature on each page; also you can't downscale pixels without breaking them, as evidenced by your preview (crop a 100px section from the original piece instead).

Mixed resolutions generally aren't nice (chariot handle).

Also 87 colors: there is something pretty xrong there as it looks like 32 at most.

Nice character and colors anyway: please fix it!