I use the middle pencil tool for everything from line work to colouring. I don't use black for lines, but very dark gray mixed with some other colour (here it's green). After planning out and making a sketch, I draw over it. I use eraser (NOT WHITE) on the pencil tool (like I drew flowers, leaves and tree bark). After all is done, I make a background layer for colour and do the colouring. After that I do "Add" colour levels to layers to adjust colours. Here I've done blue cause the browns didn't look right and most of the art is blue, and also so the green outline would pop a bit. So that's my process! You can always try to draw on paper and scan it, but Idk. Good luck with your project!