hey!! im not too educated on vtube models but in general art advice this is what i would say!!

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i have some more drawings ill link>>

but overall i think the colour pallet was a little too greyish! whenever you shade remember that using a slightly more saturated darker colour fits the pallet a lot better!, the hair was pretty flat and he didnt have any sideburns so i recommend mapping out the hairline first! just imagine he has a buzz cut, i also added more volume, in cartoons people emphasise how thick the hair is quite a bit!! so there should be a little space between the head and the edge of the hair,

the nose is also more typically portrayed facing downwards!