When using a lav mic, tie a very loose knot in the wire that will help control the mic from being jerked around if it is pulled on, which can cause the mic to rub across the clothing making a nasty noise.
When using a wireless transmitter in the heat of summer, wrap the transmitter in a non-lubricated condom. It will keep condensation out.
Non-lubricated condoms are also good protection when transporting lenses in sandy or dusty environments.
from: Eric J. Smith
Director/Director of Photography