I used to draw a bit of chibi during my "OMG ANIME?!!!!" phase a couple years back in which I relentlessly downloaded and watched gigabytes upon gigabytes of fansubs. Gladly, I'm over all that now

From what I remember, just draw two circles on top of one another. Bottom one is body, top is the head. I just gradually continue filling in details, keeping everything as simple as possible - then add detail. I tend to keep the hands and feet extremely simple and snubbed.

If that isn't all you need, then I think PolyKarbon has a SD tutorial. Not entirely sure - but my guess it does.