John,
Not too technical, but my ball park method is thus:
Set VTA to parallel and set VTF to what the cart manf. recommends (arm and cart both parallel to the platter).
Then, if the sound is too thin, I either raise the VTF or drop the VTA (lower the tonearm).
If it sounds too muddy, I lessen VTF or raise the VTA.
Of fourse, first you have to align the cart. I use the free protractor available at
http://www.enjoythemusic.com/freestuff.htm.
GL.