If you have ever been asked to cover an exhibitionor show I wouldn't blame anyone to in waning to turn it down. Unlike portrait or product photography you have virtually no control on the subject, lighting or the crowds bumping in to you!
At most indoor exhibitions you are required to obtain a press pass, not always easy but it does come with its advantages. I recently coveredCrufts 2011 which was a big challenge.
Not only because tripods were not allowed and the lighting was awful but because trying to get images in crowds that are constantly bumping in to you is not easy!
My first piece of advice would be to arrive early before any of the crowds arrive of at least before the bulk of the crowds roll in. Scope out the main areas where you will taking photos for lighting and white balance as well as potential access issues due the impending crowds. Either note down the settings you need or as I do use a small memory card as my white balance info on it already taken by you from test shots. That way when you go to take your photos later in the day you will be setup in no time!
Socamera settings. Most exhibition halls will have poor and random lighting. A flash gun is an absolute must. If you are taking photos of subjects that move quickly or you can potentially stumble on TV interviews etc use high speed sync flash and free off a high number of images to ensure you will get some keepers. You may want to consider a fairly low f. number and maybe even bumping up your ISO if conditions are really bad.
Unfortunately at exhibitions and shows large crowds are almost guaranteed. This makes getting the right shot pretty challenging at times. Having a lens that allows you to keep more of a distance from you subject can be beneficial as you can find a spot that helps you get less involved with the crowds. Sometimes though you need to get up close and use the advantages of our flash so you really have to stand your ground and just go for it. Be prepared for the odd idiot to bump in to you, just be committed on the shot and fire off some quick images to ensure you get the shots required.
The best piece of advice I can give is keep mobile,photograph anything interesting and talk to everyone. You never know what shots you will end up with!