Very carefully. Seriously, as a bassist for over 50 years, I was in the era when the only tuners were strobe types Conn, or Peterson (I still have a petey) and they were more expensive that the instruments you were trying to tune.
I was blessed with pretty good relative pitch. More than a half on century listening to Bb in marching bands, as well as playing songs in the key of A. In quiet, I can get really close 95% of the time. For tuning string to string I can use harmonics playing the same pitch on two strings, tuning the untuned string’s tuning key listing for the wobbles slowing down. When it stops, the two strings are in tune with each other.
But why go through those histrionics when a plain Jane guitar tuner is much more efficient? I always tune to open strings, no particular direction up or down.
Glad you have a system that works for you. It’s and interesting process.