Start early. Because children acquire new languages far easier than adults, parents of deaf children should begin teaching ASL as soon as possible. Research suggests the first six months of a child's life are crucial to fostering language skills. (See Reference 2) If you're an older person, however, don't despair. Recognize that you'll need to be patient and disciplined as you work to adopt not only a new language, but a new method of communication.
Immerse yourself. Sign up for a week-long immersion retreat, where the only language allowed is sign language. Attend immersion seminars and improve your vocabulary while meeting others in the deaf community. Some universities offer ASL residency programs during the summer, where you can spend two weeks or more immersed in ASL. Even if you've already taken multiple classes, you'll be surprised at how quickly you learn once your communication is restricted to ASL.
Contact your local or state school for the deaf. Many offer residential and day programs, outreach programs, vocational opportunities, sports programs, theater events and other specialized services. Getting involved with deaf communities is an excellent way to advance your level of fluency in ASL, while educating yourself in the human experience of being deaf.