The secret is the "pinch" - take the sealed sewn end of the shape and pinch shape apart at right angles and to use a chopstick. I'll explain....
Step 1 - Sew and clip the curves of your shape. Use a small stitch length as this gives the best and strongest curves. Clip around the shape. I use pinking shears (they are so quick and neat).
Step 2 - The "Pinch". Grab a pinch of fabric on both sides of the sewn shape near the sewn in section. This means you are pulling the fabric apart at right angles. This forms a little pocket in the fabric.
Step 3 - Use the blunt end of the chopstick to insert into your little fabric "pocket" and push through the shape.
Step 4 - Run the blunt end of the chopstick along the inner seams to smooth the shape.
This method works well with all sized shapes as on the smaller dolls below (although for the very small shape I prefer a blunted satay skewer to the chopstick as it's a lot smaller).
I always press the turned shape before stuffing.