I bake my sculpts over a bed of stuff (Polyfill) and am sure to support their bends and extended limbs with more fluff. I'm still shopping for a convection oven I like well enough to use for all my sculpts. In the meantime, I use a home oven, and bake the sculpts in this roasting pan. It minimizes the amount of chemicals that get into the oven itself.
Here is a shot of Kyle before and after he is sanded. In the second picture, he is still wet from the wet
sand paper I use. I start with 320 grit and work my way to 1000 or so. I have up to 1500 left over from when I used to make jewelry and barrettes. I usually don't make my sculpt THAT slick...they'd be glass-like. But, one pack of this paper lasts forever!
Notice how he's pretty lumpy in the above pictures. I always sand. Polymer clay expands a bit when it is baked so no matter how smooth your sculpt it, the clay will come out a little uneven, due to the way it expands.