I'm gonna mirror what Marcus has said. Make big changes first to really feel the difference that each makes. Leave the 1-2 click adjustments till you get a much better feel.
Also try to be as consistant as possible when testing. That is to say, try the setting on the same portion of the track and same line. You should be intimately familiar with this track to start with, as this will help eliminate some of the variables involved. A video camera really helps, as you can slow down the playback and see, with more accuracy, what is really happening.
Get your spring rates sorted first though as this is the "foundation" of all your work. Sorry, can't help with PDS.
Keep good notes and back up each test with a stopwatch. Sometimes, what "feels" fast, is not actually fastest.
Patience is the key, both from the tuner and the rider. Riders tend to get bored with this type of testing very quickly...big difference between "factory" guys and many "normal" racers.
Sorry if this sounds wishy washy, but it really is a feel/ experience thing (and a bit of hocus pocus :think: ). There are some good tuning guides out there, MX Tech, as one example, that work well to help guide you, but will not be as straight forward as they often sound in real life. Use them as that, a guide. At least, with some luck, you'll be going the right direction :thumb: