Behaviours...........oh the waste of time and effort that has gone in to focusing on these symptoms over the years!
Just be aware that behaviours all have meaning and are used for a purpose, usually as protection from the world that is far too stimulating. Use them as a means of communication: they are a clear message of what is happening to the person in the moment instead of something you need to fix. Recognize their connection to the level of anxiety that a person is feeling and you will do the person with autism a world of good.
If you want to educate yourself further on this issue, please go through the slide show found at Autism: Getting the Truth Out. Yes it's long, but it is an excellent presentation on this topic. Note: I have moved this from a link to a suggestion to search it on the internet as it seems to keep moving.