I don't know what your skill level is but I find the Signing Naturally series really good. They come with dvd's too which is a big help.
[ame=http://www.amazon.com/Signing-Naturally-Student-Workbook-Expanded/dp/0915035200]Amazon.com: Signing Naturally Student Workbook: Level 1, Expanded Edition: Cheri Smith, Ken Mikos, Ella Mae Lentz: Books[/ame]
These books are most often used in the classroom but I do just fine on my own. I'm in level 3 now.