The method I have started using recently (Can't remember where I picked it up) was a piece of genius and transformed my test strips effectively in to "stops" of light for each part of of the strip. This meant I could think of modifications to expsoures in terms of stops of light just like a camera.
Take the strip and place onnthe easel and expose all of it to the negative for 2 seconds. Then cover up a small part of the strip and expose for another two seconds. Cover up a little more of the strip and expose the uncovered part for 4 seconds, cover up more of the strip and expose the uncovered part for another 8 seconds. cover more and expose for 16 seconds etc...
What you end up with is a test strip which is exposed as 2,4,8,16,32,64,128 etc....you can take it as far as you think your negative needs it. If you think your chosen strip is half a stop too dark then you can take half a stop off. Voila!
The pain is that you need to keep changing the timer, but I have found it saves me more paper and time since it covers a wider range of exposures and allows me to judge what is needed from a dodging/burnig point of view.