Here's a corner of a sketchbook page about a character that I might use.
It always takes so much planning and research until I can start on a "finished" illustration - that used to worry me a bit, now I have realised that's just what I do. Many illustrators seem to work out the pictures in their head and then draw them as they imagine them. I am always impressed and think they must have very visual minds...
I don't think in pictures at all, in fact it baffles me every time that my hands know how to draw something that I haven't imagined. It's like I think the word "dog" and draw a dog without imagining a dog clearly first, and normally it looks a little bit odd that way.
So I need to work out what every item in the picture looks like, and why, and how every character feels, and why, and who they are, and if they often feel like that. I also need to do very detailed drawings of the characters so that I can then draw them again and leave all the detail out. Makes sense to me - if I don't know what stuff is, how can I leave it out properly?
So I do an incredibly small amount of actual finished artwork... my illustration work is 90% research and planning and 10% roughs and finals.
It's almost artwork time now for two books, which is very exciting! You should see the stacks and stacks of notes I've got and then look at the doodly did-this-in-a-minute final artwork that comes from it, you'd laugh.
Weirdly, I dream in pictures. In fact, I think that is the reason I draw things, I am trying to show things as they are in my dreams. I think that's why I never feel a great urge to draw stuff I like in the real world (except for odd things that I really really want to remember) - it already exists, and that's enough to make me happy. But my dreams only I can see, and I forget them soon after I wake up except when I'm drawing and writing...