I don't have a lot of experience with people who have autism, but from the few times I have, I've learned two things:
~Don't underestimate them- most of the kids I was with turned out to be much smarter than I had anticipated
~Always be ready to deal with anything. People with autism have different perceptions than people without it, so they could be feeling things much different than you or I.
I don't claim any expertise whatsoever, this is just based on a couple of times being with a group of kids with autism. Hope it helps