If descending into an area that you are unfamiliar with in IMC or night, keep an eye on the radio altimeter. In most cases just before a GPWS "Pull Up" warning sounds, the radio altimeter will come "alive" and show rapidly decreasing RA height. If you take immediate emergency climb action right away without waiting for the aural "Terrain Pull Up" warning, you may save a couple of hundred feet and that may save your skin. We practice this in the simulator and it works.