I just read a great excerpt from Jewelry Making Daily - by Tammy Jones - 

on many notes she had made from Kate McKinnon's books and interview - 

 

 

1. Imbed structural elements like ear posts and ring shanks in your work instead of attaching them with slip or solder. This will make stronger work that doesn't have solder joins to worry about as you're finishing your piece.

 

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2. Forming metal-clay pieces uses ceramics techniques, so a book on hand-building clay is a good resource for learning or remembering those basic principles of working with clay from sixth-grade art class, like rolling smoothly, eliminating air bubbles, compressing edges with your fingers, and how to "think like a particle herder." Kate's "slip-free, dry-slab constructions" are formed with pure hand-building techniques which, she says, "are the foundation of good metal-clay skills."

 

3. Hand-building clay brings me to the next silver metal-clay tip, which I first mentioned last week. Kate suggests beginners to metal clay should use porcelain clay to practice forming techniques, because the two clays have similar drying and cracking rates and feel about the same in your hands--porcelain clay is just much less expensive.

 

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4. When you're kiln firing metal-clay pieces, remember that you aren't just burning off the binder; if that's all there was to it, it would be a quicker process. The key is to raise the metal-clay pieces in your kiln to full temperature (1,650°F) and hold them there for two hours. Kate calls that a "deep annealing soak" that allows the particles in your silver metal clay to merge--and that will transform your clay piece into a dense, strong, solid metal piece.

 

5. The more attention you can give to your fresh clay, the less attention and work it will need when it becomes bone-dry "greenware" clay later, or even later when it's fired metal. Work on one piece or component of a design at a time and finish it as well as you can before firing it. One way to do that is to brush joins with a damp paintbrush to gently smooth and clean them.

 

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6. If your clay becomes unworkable--if your piece gets too dry or seems doomed for whatever reason--you don't have to discard the clay. In many cases, you can rejuvenate the nearly dry clay by rolling it with some fresh moist clay and let them hang out together in a tightly sealed plastic container overnight.

Kate recommends a ratio of not more than 10% dry-ish clay to 90% fresh clay, or it might go the other way and ruin the good clay instead.

 

 Sculptural Metal Clay: Techniques + Explorations and The Jewelry Architect: Techniques + Projects for Mixed-Media Jewelry, as well as from Kate herself with Jewelry Making Daily a while back.

http://www.interweavestore.com/Jewelry/Books/The-Jewelry-Architect.html?SessionThemeID=20&a=je110418

Also, there is a metal clay group on yahoo groups : MetalClay@yahoogroups.com.  Lots of great folks who help newcomers, and share knowledge. I have never use Prometheus, but some on that Group have and discussed it. Join up and you will hear from many.