We as a society need to work together as an extended community. We need to be proactive in our understanding of each other. I believe that it is more important to learn the communication system of a person with disabilities then to try to force them to learn ours. We should be the students and let them be our teachers. I believe that in most cases behavioral problems stem from either needs not being met or lack of communication.
Terminology is also very important.
Refrain from using words such as retarded when talking about people with different mental abilities. It is better to say a person with autism then to say an autistic person. Look for similarities in people instead of differences. Understand that there are many types of communication besides verbal. Try to grok the definition of abuse and avoid it.