That is quite a good article. Boils down to thinning the paint just enough which to me comes down to trial and error and experience.
It mentions warming the paint up which I can't see being practical for conventional spray. Once the HVLP turbine has warmed up my Fuji sprays with quite warm air and I can get away with slightly thicker paint because of it.
I always use a viscosity cup to get the right runniness, after I have given it a proper mixing of at least 4-5 minutes and passed it through a paint sieve. those 3 steps make the world of a difference for me