May I jump in? I checked out an episode of your comic and you have some coloring skills--more painterly looking. I can see why it would be time consuming for you, but it's beautiful.
Like @Snowdrop said, start with flat colors, but the question is what drawing/digital program do you use?
Just for starters, I use Clip Studio Paint and an artist monitor/digital pen with it. The thing I find helpful in coloring in CSP are the menu program helps, like color pallet areas to name your character and have their color pallet squares available to you.
Then the amazing vector layer that allows you to draw the finished ink lines of your character(s) and change the sizing without pixelating.
Then with that lined layer, you can identify it for your paint bucket to easily fill in the colors in the next raster layer.
Oh, need I mention the ease of making your own custom brushes of your character's face, clothes, etc., etc., with the properties of another csp brush there that you need.
I don't know if your drawing program offers features like that, but it sure helps significantly. Or perhaps, you already access these. Bottom line, I hope I've helped.