You can do this by yourself or in small groups.  Write down as fast as possible all the negative comments you most dread overhearing about the promotion you are doing.  Imagine what you might hear if you listened in to a gossip on the steps of the library or a moan in the staffroom.  Imagine what people might be thinking even if they dare not say it. 

Don't censor - let it rip.  Write down what people would actually say in their own words, don't disguise it in abstract language.  It's ok to get the giggles at some of the absurdities people come out with. 

Think about the different kinds of anxieties you have.  The comments you write down may come from different viewpoints for example a homophobe might say of a gay promotion, 'Disgusting rubbish!' where a confident lesbian might say 'What a patronising approach!'  Library staff may be anxious on both counts.

Then go back and take each comment in turn.  If you are working in groups it's a good idea to swop lists between groups so people go through a different list of comments from their own.  Discuss what you'd say in reply if someone really did say this to you.  Write down your answers.