I also found the following tip useful when approaching an airfield -
Look at the DI. If number of the active runway is on the same side of the DI as the circuit direction, then you are approaching the airfield on the live side. If it's opposite, then you're on the dead side - e.g Active runway 23, RH circuit. If the number 23 is on the right side of the DI, you're on the live side.