From what I've read, the idea is to work on 5-10 signs to start and add more as your baby begins signing back. It's important to be very consistent in working on signs so it's a good idea to chose signs for words that you use often in your day-to-day activities. Here's the list we're starting with:
I have no idea if it will work, but it will be so cool if it does. Besides, I'm really enjoying learning the signs. TDSH is threatening to make up his own signs though (I think he's a bit skeptical about the whole thing). If I catch him at it, I'm going to teach Abner that this is the sign for Daddy!