Initially it begins with a very simple idea or message. This is often very loose and oddly for a painter who paints a lot of architecture the characters can come first. These are often based on people who I have met or seen as a normal part of my day. They are often drawn on the spot, simply developed at home without any reference or photographed if I have a camera handy. All pretty rough at this stage.
I have started to put together some ideas on characters I may want to use below. Many will be abandoned for good or reincarnated in a later picture.