unfortunately I forgot to save each step of some of more recent examples, but generally, heres how my icon process works

1. sketch + og colors (I can either start from very crude doodle or go straight to almost clean looking sketch. usually depends from how complex character or pose is)
2. lineart + new colors (pretty straight forward. I usually just clean up already existing sketch and saturate colors by picking them by hand. I dont like using filters)
3. shading (most time consuming. I try to limit my usage of colors as much as possible and try to reuse every color from original palette)
4. details (background, hands or particles usually get added last)

not quite a tutorial, since I dont really know how to explain every little detail I make in step by step manner, but hope it was still interesting to you