Set the radio altimeter to max warning height before top of descent especially at night. If no warning height just note when it first indicates 2500 agl. Useful as a poor man's GPWS especially if a big yellow light (if installed) suddenly comes on telling you that you are currently 2500 ft above SOMETHING that can kill you. We used to set it to full scale warning in the 737-200 soon after take off.
Descending into Honiara from Brisbane at night the warning light would flash on as we passed over the big mountains in the centre of Guadacanal. Very useful situational awareness lesson.
Regardless of arguments re use in NPA or ILS, the instrument can be a life saver providing you keep it in your instrument scan and pick up it's first movement from top of the scale.