CHEAT!
Duplicate your ink/line layer.
Choose a color. Make sure to protect the dupe layer so you're just coloring the lines (like protect pixels, lock layer, etc). Make that dupe lineart layer have the color you chose.
Set the dupe layer to Overlay.
Go back to the original layer. Lower the opacity a bit.
You shall then have lines that have a overall tone as well as show a bit of the colors underneath. You may have to go back to the color layers to fill them out a little depending on which color bleeds under the line, but it's a cool effect and saves time...at least to me ^^;
https://www.deviantart.com/looji/art/My-full-drawing-process-812881831 <- I stole the lineart trick from Looji on Dev Art 