hey,
well my thoughts on this are what ive been taught what to do very recently and i am for doing it with every piece, dont use lineart to start off, start with lower values and make your way up. i am for this because it does get the job done quicker.
i've also noticed that your colors are very close together (there isnt much contrast, i think its that one) using more contrast will make problems like clashing colors, so on so on. but, without the right contrast you will turn into a me and people dont like me's.
your dithering, your dithering style is very unorganised, yes it does make it smoother, but work on volumes now, and then work on dithering and smoothing, don't get carried away, set yourself a time frame, say like: in one hour im going to post my progress no matter what stage im at.
so summarising: remove lineart, get more contrast, remover dithering at this point.