After I've outlined everything and cleaned up most of the pencil sketch, I get to color! This part can be so relaxing. First I choose my color palette. Paper lets you mix colors in a few different ways, and also has an eye dropper tool. Usually I create a little palette of colors in the corner, with a light and dark shade for each. I color with the marker tool in Paper. The marks come out pretty opaque, but does have a multiply type effect when you layer color on top of it. Because of that I try to fill in color in one, continuous stroke, without lifting the stylus. I'll use the eye dropper tool to pick up the colors from my palette as I need them.
The next step after coloring is to do the final layer of inking. For this I use the calligraphy pen in Paper, set to black. The stroke weight varies depending on the pressure you apply, so it's good for getting thicker strokes, with some variation in weight.
The last steps are to pick my background color, and then add in the shadows and sign. Paper lets you drag and drop any color onto the page to change the background color. Once I find a color I'm happy with, I use the eye dropper to pick it up, and then mix a slightly darker version of the color. I add in the shadows, and finally add my signature. If at any point I'm not happy with the position of something, I can use the scissors tool to select an area of my drawing and move it.