This is nice image
Also yeah forget thin lines
The way to deal with thin lines is to use the magic wand to select outside of your objects/characters, and raise the tolerance until the selection has a good enough coverage, then invert the selection and then fill in the selection with a "base color" on a layer below the outline layer
Then it helps to have a color layer above the base color layer that's set to being a clipping layer so that you can scribble around your outlines yet never go outside of them because of the base color layer setting the rules for the above color layer
