The simplest way to ensure that, say, a predominately light subject (or dark subject) comes out light (or dark) on the slide or print is to take an incident light reading. This measures the light that hits the subject, not the reflective properties of the subject.(posted 9871 days ago)However, the _best_ way (ie most reliable, with greatest control) is to take a a reflective light reading of different areas of the subject (which is easy with a spotmeter) and decide where you want to place those tones on the characteristic curve.