So What you wanna do is get Lineart finished first
So steps for a normal piece are like
Line Art > Set Layers Below Lineart
Coloring for different sections should be spilt apart like Eyes, Clothing,
Hair, etc.
For a different tonne color it is: Layer of lineart, lower opacity, choose any color and color over drawing. (You can choose different colors
)
For Coloring Lineart do: New Layer, Above Lineart, Clip to Lineart, Choose Color(s) and color over