What can I do to be an advocate for the disabled?

Speak Up... As an 'advocate' i find the best advice is to be a voice for those whose voice gets lost. Assist and be supportive in any way that you can; but continue to be proactive in your support and never be fearful of taking it to the next level. As long as you have someone's best interests at heart you will never be faulted for your 'advocacy' and for doing the right thing.