Ideas for colouring and making 3D looking edges with highlighting and shadows.

I am new to Fresco and digital art as a whole and I was wondering if there was a technique people use to turn their line work into a coloured/painted image.

I would like to achieve more of a 3D look to my drawing by getting rid of most of the black lines and instead having colours meet in a straight line rather than having the black lines separating them. From there I would like to have opaque highlights and shadows where the black lines used to be.

Is there a straightforward way to do this that I am overlooking and are there any other colouring/painting methods I could use to achieve what I have in my head? I have attached a screenshot of my line work and a colour-filled version for clarity.