These are the steps on how I do it in-game during Asylum / High school run.
Guide to Find the Ghost Faster
Mainly this is gonna be a small guide, but lets run with it. This is the steps that I run on either asylum or highschool for the best experience or a way of finding the ghost the quickest way possible.
Walk inside the building with the team (High school / Asylum).
Ask either one of your teammates to stay with you or go back to the truck. (Ask to go back if ghost is alone.)
Walk down the hallway with the Thermometer and say in local voice chat "Give us a sign" (or say "Give me a sign" which works better).
Keep saying this until you find a room with a light on or either a room that has the door open.