Holy-
Well, usually I have outline, color, and shading layers, adding to that the sketch layers.
MIGHT sounds overkill, but hear me out :
Step 1 : draw sketch of the character. Aka his anatomy. You can out as much circles, spcheck and cross you want. You wanna have a global idea on what you do.
Step 2 : make the stetck transparent and do the REAL outline. There it's clean and coherent.
Step 3 : Color it on another layer, so your outline doesn't mix weirdly with the color.
Step 4 : Shade it however you want. If you use Add or Multiply, you WILL need new layers.
Ofc if you're doing silly sketch you don't need allat, just put it on one layer 🙏