I have been involved in event photography for a number of years, mainly for business conferences in Europe, Asia and the USA. The events are usually similar, with keynote speakers, round tables and workshops, but the conference setup can be totally different, especially the lighting. It is important to be present at the location before or during the setup, to find out who is doing the A/V audio/visual (this guy is your friend), see how the lighting is setup for speakers, presentations and film clips, and also check the lighting in the seated area where the attendees sit in the main conference room. You should also test your camera with and without the flash, and find the best place in the room to setup your tripod. I have found it is always good to tape the floor around the feet of the tripod using safety hazard tape, to save anyone from tripping or disturbing your camera.
Some important points that I have learned.
When working as the photographer of a conference you will need to dress as if you are an attendee. You will also need to know the schedule, and have a copy with you throughout the day, find out who are the key players at the event, and mark the times that they are speaking, get your light right, know how your camera reacts in low light situations, and mingle but keep your distance. Smiling really does help you to get closer to the people you are photographing.
Taking extra photographs of the empty rooms, main hall, and food, can be of importance to event organisers for their future event planning. I have worked for event organisers for a number of years, and using these photos helps them to plan future events better.