Advice for a movie theater usher?

I just started a new job as an usher at a movie theater. This is
actually my first week and I have worked all this weekend. We have 10
auditoriums and I'm not used to being on my feet, so I've been falling
behind. Sometimes I don't manage to get all the theaters clean before
customers start coming in.

So does anyone have any tips or advice on how to get the theater clean
faster? I am supposed to work 10 hours today and I'm the only usher
working today so I don't want to screw up and fall behind on the
schedule.