"If you're "all over the place" on your ski (as I often am) there may be no amount of tuning advice that can do much good. That said,if you can get your hands on a copy of Schnitz's original tuning list - which at my lake is actually referred to out loud as "The Bible" - you will have the very best guideline I've seen in 20+ years of ski tinkering."
Since my water skiing exp is limited let me draw from my vast knowledge of snow skiing as I have been doing it for 40 + years now and racing in my younger years.
I can pretty much take any ski in half way descent condition and tune it to work for me but I can a take a good ski set up to rip for me. I can put a someone of less experience on that same ski and they hate it. As TW stated above all the tunning in the world will not compensate for bad form. That is why I am at factory numbers on my senate and working on my turns right now. I want to have the best equipment I can use right now but I think continually tweaking my boot and fin position to get the ski over my body position is a bad idea right now.
My 2 cents
That being sad where can I get a copy of the Schnitzer's org tunning guide. :)