Well a first step would to not save your pixel art as jpeg
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To make sure the shape of your can is consistent with each other on the top and bottom, it'd probably be best to draw the circle of the top and copy and paste it for the bottom. One thing that's driving me nuts is how the sides of the can aren't evenly-aligned with the sides of the circle.
Also, pure gray is almost never good, try to put even the smallest of saturation in there. And full saturated colors=pain on the eyes.
Here's a quick edit I did. Just note the changes I made, I added shading, and made sure to try to keep consistent with the light source I chose. The anatomy on the hand probably isn't right, I dunno, I never took any anatomy class or studied it aside from holding up my own hand. It's a pretty basic edit though, as the can is pretty boring and I didn't add too much to make it interesting.