Densitometers work and may be of benefit in many ways. However in my dark-age darkroom, I rip up a sheet of whatever and use a piece approximately a quarter of a full-sized sheet, and place it in a critical part of the image. Usually it requires no more than a couple of trials to acquire the necessary data (by inspection) to home in on the required contrast grade and exposure for a test/working print.
Caveat: it requires a lot of paper to arrive at most of the fine images you see, here and elsewhere. So be patient and expect to use some paper.