Step 1: Starting out
I quickly sketch out a character position and then select new layer and draw the next character. I do this because I can then edit the size of each character later without any disturbance to the rest of the picture. When using a new layer if your characters overlap you can lower opacity of the lower layers to help you out. The opacity is on the right side of the selected layer in the layer window. I sketched a rough background as well to get a feeling of the drawing.