I read all the tonearms and cartridges instructions that I can get my hands on thanks for vinylengine.com.
Basically, the tonearm (SME and others) need to be parallel with the record during play, and the cartridge body needs to be perpendicular and form a 90 degree angle with the record plane (in the case of Grado), then you have Mike Fremer's SRA, VTA stuff.......
I've decided to forget all that. Empire tonearm can never be parallel with the record during play if it has a grado on it, because it'll never clear the record when move the tonearm over it.
Now I adjust the tonearm by ear, lowering the tonearm gives you more bass, and raising it gives you more treble, I adjust the arm when the sound is balanced, and neutral, of course I use my reference record (Nautilus Joan Baez Diamond and Rust) for this adjustment.
The result of this method is far more satisfactory than measuring and peeking at here and there.