depends on ground speed on approach; for a prop like a Connie or DC-4, approach speed 105 - 115 KIAS no wind, try bracketing about 500 fpm.
typical jet with approach speed around 140 KIAS no wind, try bracketing 800 fpm. In any case, try to be smooth with VSI in tracking the glide slope - stay trimmed , try to vary VSI no more than plus or minus 200 fpm from target descent rate and you will soon see what a good rate of descent for your approach speed will be. Also try to be smooth with power changes, they can really cause problems with trim and speed changes in some airplanes.