For starters, make sure you set it in the attack position, weight 99% on the pedals, bounce a few times to get through the stiction and then push the O-ring down whilst standing with your elbow against a wall. After you’ve added or removed air do plenty of bouncing to equalise the negative spring before measuring sag again.
I seem to usually find that around 20% sag works well for me. The air spring curve makes a big difference – I’ve noticed a 140mm Pike is much easier to get feeling good than the same fork with a 130mm air shaft, the latter being less firm when pumping but harsher through the bumps. If you’re lighter or heavier than average it’ll be harder to set up and may need a custom tune.
Bottomless tokens are often misused – they ramp up the last bit of travel so you won’t bottom harshly but they make the midstroke comparatively soggy. Better to add more air.