You've got a good start, so props for that.

first and foremost the best advice i can give you is to avoid dithering. it is best used only and exclusively on two scenarios: one of them is giving texture to a rough surface and the other one is working under strict palette restrictions. the reason for the later one is that dithering per-se is not part of the shading process itself, but instead one of the techniques you can use to ease the transition between colors when you can't afford to use one tone to do that work(something that often happens when you work under palette restrictions).

this is however completely up to your own experimentation, so don't take my advice as something set in stone: if by experience you feel comfortable with how dithering works for you then by all means do your best and work with it.


the second piece of advice i can give you is to read about volume and shading. your sprite has a minimum amount of shading but it is barely trying to convey the actual shape of the character or the volume of his body - something you achieve by means of using highlights and shadows. either look upon tutorials(like the one here on pixeljoint) or look around you as to how light and shadows interact with the objects around you. the human body is made of multiple shapes so it might be a bit hard to follow, but simpler objects like cilinders and cubes might be a good study on the subject.

lastly, just remember to enjoy and have fun. pixel art is all about practice and enjoyment.as long as you want to challenge yourself and have fun while doing so you'll fit right in in the medium.

good luck o/