Here's what I've gathered through my handful of runs. It's gonna be a ramble-y mess and pretty long. Hell, it may be entirely wrong for all I know, but I typically get it narrowed down to 2-3 ghosts by turn 7 on the easiest difficulty. These tips may help on higher difficulties, but they're not as reliable.
Start with checking for the ghost location. Use fetters on everyone at least the first turn. The fetters also will give a hint if a ghost is in the adjacent room, so space everyone out so that there is someone adjacent/inside every room (or as close as you can get). This can be more difficult on the second hunt. You should also use your AP on the first turn on the seismograph as you might get lucky and get a reading.
Once you have the ghost location pinned down start by changing everyone's equipment to whatever you want to check (I recommend EMF/Blacklight/Fetters first, only equip fetters if you didn't get the ghost info for fetters on the first turn) and getting the girls to set up any mixture of Seismo/Camera/Ouija (Ouija only if you plan to end your turn there) in the ghost room, the you should use your AP on salting either an adjacent room or the room it's in. Adjacent rooms allow for you to attempt to burn an incense to check for good intentions by burning the corresponding incense in the salted room. Salting the ghost room itself will only block exit for Phasmal Condesate ghosts. However you can check for them by just equpping one of the girls you have setting up cameras and shit in the ghost room with the blacklight as they always leave behind ectoplasm when they change rooms.
Getting the info for EMF/Thermo/Spiritbox are all dependent on how the ghost behaves. You have to get the corresponding color event for them to check for info. EMF is a yellow event, Thermo is blue, Spiritbox is purple. Sometimes you won't get a blue event until turn 9 and that's rough, but if you've been keeping track of the ghosts behaviors you might be able to piece it all together. Left lights on just to have them get turned out? Might be Light Sensitive, keep leaving lights on until you piss it off enough to break a light (I've never had this happen but the evidence tip says it can). Also check for EMF if you thing they're Light Sensitive, if they're low EMF they can't be Light Sensitive. Is the ghost occasionally stopping for a turn in a room? Might be Intelligent, so check for Intentionality by burning either the Red or Green incense in an adjacent room and seeing if they come to it. Intelligent ghosts must have Intentionality, so if they don't you can rule out Intelligent altogether.
This next part might be a bit confusing, but the game is made so that finding any piece of info can help narrow down other pieces. You can see this in the ghost evidence screen. And example is how: Hand links to Temperature which links to Ectoplasm. And this is because positive Temperature must have Hand or Ectoplasm evidence. Not every link guarantees things, they just mean that the evidences are have some effect on one another. Using this system to the fullest is something I haven't figured out fully, but a good starting point is to try to spread out your evidence early. Using the tools I mentioned and the equiment I suggested earlier if you get really fucking lucky on turn 2 you could in theory get: Fetters Positive, Hand Positive, Salt Negative, and Low EMF all at once. This would immediately leave only 3 ghosts to choose from. And since you know certain things are related to one another you know not to check for: Seismic, Light Sensitivity, Physicality or Ectoplasm. (Ectoplasm and Hand are a little weird, they aren't directly linked but they can't both be evidence). This would leave you 8 turns to check the remaining 5 evidences.
This is all the basic stuff I've gathered from trial and error. Lots of error. It's still not a perfect strategy, it won't guarantee a win. I also won't go into when to use the White and Purple incense, I wouldn't even know where to start. Try the strat out for yourself if you want, I'd love to hear how it can be improved or what is wrong with it.
TLDR; Just find the ghost. Check for evidence. EZ.
G'luck and have some fun with it, would ya?
