I generally begin with either a sketched drawing or a finished drawing. It's easier and faster to draw traditionally than digitally. If it's a sketch- then I will not keep any of the line art. It will just be used for a concept. If it's a whole drawing with good lines, then I keep it. To keep the lines, I scan the drawing with a printer and turn it into a high-quality jpeg- using the max resolution my printer will allow. I then open the whole drawing in photoshop and follow the steps below to begin to paint it. My full digital painting process with no time lapses is at the bottom. Depending on the complexities of the drawing it can take anywhere from 2 hours to 8 hours using these methods. I have spent over 20 hours on just a drawing before I learned to paint and draw digitally (see below drawing- it is also very large as well).