They ARE simple! Use whatever time intervals work for you. Fixed intervals, f-stops, whatever. All you're trying to do is make a test print that gives you useful information. The keys to a good, intelligent test strip/print are simply:
Originally Posted by Jonathan R
1. The exposures go from obviously too dark to obviously too light
2. There is enough image in each of the exposure strips to give you some good preliminary information on both exposure and contrast. ie: don't skimp out on paper and try to use some little piece that only covers a sliver of the image, and don't make 25 exposures 1/4" wide either. You can't tell anything this way. It is best to start with some wider intervals, and then refine from there. For example you might do a first test strip that goes from 5s to 25s seconds in 5s increments, decide the right exposure is somewhere in the 10-20s range, and then make a second test strip that goes from 10-20s in 2s increments. That sort of thing.
It is also helpful to keep the test strips because in addition to helping you find a base exposure time and contrast, they can also help you figure out how much burning and dodging might be necessary.