I don't linger. If I can't get something in 5-7 minutes, I don't get it. Usually it's 2 minutes or less. Hanging around for longer periods of time increases your chance of confrontation. You don't need any special tools or equipment to dumpster dive.
Most divers use some kind of grabber stick.
Identify yourself as a Dumpster Diver to get the discount. They accept credit cards by phone, but you can mail a check. They are very nice folks. Your Unger will pay for itself the first time you use it. Put a coat hook into the end of a wooden broom handle.