Not really a tutorial, just the way I do chibis.
Since this chibi came out only because I wanted to do a small example of the way I draw and I have no intention of colouring it, you can ask me the lineart to colour if you'd like to. Just send me a mail to email@example.com. I only ask that you credit me in the artist's comments.
1. Circle. Simple enough.
2. Trapezoid-conic-thingy for the body. Hips larger than shoulders mean cute-chubby-look. Of course, if your character is long and thin, it's going to look strange.
3. General outline of arms and legs. *Now* I decide the pose/what the character is doing.
4. Lineart on many layers. Yes, I do it all at the same moment. (One layer for the head, one for the body, one for the accessories.)
5. Fixing mistakes... (I fixed the mask, the hole's perspective, the legs and the overlapping outlines.)