peachypants this is how I manage it:
It takes a lot of time and patience. We start off with social stories. This is a way of explaining why thing happen, and what to do if things happen if they don't go the way you expect them to do, e.g.
In queues, people will queue in a line. This is because the first person in the line will be seen to first, then the second, then the third and so on. We have to be patient. As the people in the front of the queue are dealt with, the queue wil get smaller and we move closer to the front of the queue. Eventually we will get to the front of the queue [give time guidelines ]
Some people may get frustrated being in a queue. This is because they don't like waiting or might need the toilet or don't like being touched. Everybody doesn't like like queuing because they would rather be doing the thing rather than waiting.
If you feel sick or frightened when queuing, tell somebody. You can stand outside of the queue and let somebody queue for you if that is somebody you trust and will hold the queue for you. If it is so frightening that you cannot cope, then we can leave the queue but we can't rejoin the queue at the same point so will have to go back to the queue to start again.
By explaining the choices and explanations makes it easier, but doesn't necessarily take away the anxiety. In those circumstances it's better to walk away. Plus you cant always develop a social story off the cuff, if the anxiety has already started its hard to get them to listen and act rationally.