Paint the artwork by 'paint backet tool'. Although there are 'close
small gaps' mode - you may feel it cool - I'm usually using 'don't close
gaps'. 'Close small gap' is slow and imperfect - it makes small
unpainted region at acute edges, and I feel quite tedious to find and
fix them all.
After you painted all regions, delete the extra cyan strokes - just
doubleclick the strokes and press delete key.
Fine highlight and gradation can be added at this stage. I think it
is better to keep such kind of decoration necessary minimum, since they
may kill the entire artwork.
That's
it!
Good luck with your art!