Connect every computer to every projector and sound system
Connect every modem to every phone line
Connect the video conference link (even if it costs more)
Advance through every slide program using the remote
Test every microphone with every sound system.
Walk around the room while talking into a microphone to check for feedback.
Use fresh batteries in everything (and have a spare in your pocket). This includes microphones, remote controls, laser pointers, etc.
When using the house sound system in partitioned rooms, ensure that all the speakers in your room are on, and that you are not also broadcasting into the next room.
Tape down all wires. This prevents trips, disconnects and lawsuits.
Find the hotel A.V. wizard (or union chief) and become their best friend. You must know how to reach them in an emergency.
Have 2 designated hosts per room. That way, one can go for help while the other keeps things under control. Ideally, one should be able to assist the speaker