I haven't done hand embroidery since I was a girl, but I have a friend who does beautiful, beautiful work. For the most part she uses regular quilting cotton, but she fuses something called form flex (or maybe it's flex form? no, I think it's form flex) to the back of the fabric before she starts. It's a lightweight stabilizer. She said she likes it because it hides shadows from traveling and knots, and gives the fabric some body and stiffness to hold up the embroidery. Hope this helps
