So, when my partner for the Whedonverse swap had the quote "I want to keep Spike as my pet" I knew what I wanted to do:
I decided to do more of a character of him than a realistic version, partially because all I had to mold the sculpey with was an xacto knife. Here's a few of the stages:
For his teeth, I created them separately and then set them into his mouth. I wanted them to be distinct because his smirk is the best thing
The eyes took me a while. It's hard balance of realism and cartoon, so I experimented a bit, and then took the shape of his eyes and just blew 'em up like an anime
Painted with gauche because I like how forgivable it is... if you mess up you can wipe off with water. Also seems to give more depth on the sculpey than the acrylics.
Later, I very carefully sprayed him with a couple coats of laquer. This is tricky with the gauche, because it can re-wet it and cause things to pill/run if you're not careful. It made him nice and shiny, and the few bits that pilled I was able to correct before the laquer dried. The earring is a piece of chainmail I stole from my husband.
I'm pretty proud of how he turned out, I'm just starting with the sculpey this year!