As a member of the hard of hearing/deaf community, let me tell you there are TONS of books out there.
www.harriscommunications.com is one resource with many different books depending on what you are trying to learn. There will be a different focus if you're learning words a three year old will need vs. words to actually carry on an intellectual conversation. One of my favorite items in their catalog is an ASL magnet kit. It's like those word magnets that you can piece together and make sentences out of. It's great exposure since it'll probably be in a visible place such as the kitchen fridge and makes the learning easier.