First, cut out a lot of shapes from paper to do an exercise I call "Embryos". It'll help you get a starting point for new characters.
Then make some characters. Once you found one, photograph it and reshuffle the pieces, swap some pieces. Make more characters. Photograph. Shuffle. Make ten or so. Don't worry about them, just have fun. Let other people make some if they wonder what you're doing
Now look at the pictures you've made and select your three favourites or so.
Now pick your favourite again.
OK. Here he is. Now we want to get to know him.
(This next exercise is developed with Alexis Deacon who is brilliant at this sort of thing.)
Take a big sheet of paper and draw a load of shapes. Simple, closed shapes. Use a coloured pencil. Draw a circle, and a triangle, and some beans and squiggles, and some sharp shapes and rounded shapes. If you like, make angry shapes, scared shapes and happy shapes...
Turn the sheet around a few times.
Then start putting your character into these shapes. See how he fits. Don't hurt him. He doesn't have to fit inside exactly. Do the first thing that comes to mind. be obvious, don't try to be clever. Just let him do his thing. Think of the shapes as an aura he should inhabit. And give him a simple reason for these poses while you're drawing - is he bending down to look at a small thing? Is he running away or towards something? Is he asleep? Happily?
Add speech bubbles or thoughts if you like.
Right. Now you know a bit more about your character. (In this case, I can see that he is sometimes plucky, but encounters things that worry him a great deal... maybe he's a very small adventurer?)
Now that you know him a bit, let's see how he feels about the world.
Draw a line on a new big piece of paper. Make it squiggle and zig zag a bit.
Now draw your character, simply and small, on the line. Make him navigate it.
Is he climbing or just looking up? Is he tumbling or parachuting? Is he happy or overwhelmed? methodical? Confused? You'll find out.
Now give him a name.