I don't make bow centers with clay, but I dabble in polymer clay art dolls. If you are having problems with polymer clay sticking to the surface, a couple of things could be going on. I use a smooth ceramic tile to work on. Other people I know use glass. It tends to keep the clay a little cooler. The clay will warm up as you work with it, and if you find it's getting mushy, it could be that it is getting warm and just needs to "rest" a bit. You can also stick some in the freezer for a bit if it is mushy and you want to be able to work with it again quickly. Some of it could depend on the type of clay you are using. I've used baby powder (sparingly) before, but the problem with that is that once you put the powder on it, it's not going to stick to another piece of clay again very well. You may not need it to though.
Anyway, I hope this helps some. If I can help some more, let me know.