I find the best is to spread the spotting ink out to dry in linear artist' paint pallete
I have a glazed ceramic one. A drop of each colour, one per tray spot, left to dry
Then a drop of distilled water to each to wet each slightly and tip the tray and jostle it lightly.
Left to evaporate, the higher up the 'drip spalsh' the fainter is the tone.
I find this makes picking up the right amount of dye easier to judge.

I feel spotting is a necessary evil. I strive to minimize dust. Spotting proficiency is one of those skills I wish I practiced less.