You shouldn’t give up tho

It will take awhile to get a good result but you have to be patient and slow

And for highlights. Chose where the light source is coming from. I always to the top left corner. Once you have it identified highlighted every part that would reflect the light

if Something overlaps something... shade the part that’s being overlapped

I traced over the original character and added details... Gacha edit basically and I used ibisPaint X