Some tips and hints I've picked up while playing the game.
Corruption - Only really useful for creating traitors. If you want it, try to focus one or two at most you want as a potential traitor. Succubus and tempting (Dont temp too much, it increases sus to maids) Are costless ways. Food and drugs start costing magic. . Iroha, Risako and Kazuto are the easiest targets to corrupt. Mao, Mark and Josephine, Samuel I think the game considers bf/gf couples and seem to start with -20 to -35 corruption. Mind you, you get one shot at it.. but you can try when they are hostile too.
Diffuser - You start with one in the beginning of the game at the Entrance. However its not really and efficient way to use it if your trying to bait people to talk to Katanshi or distracting them. Its moveable (without magic too) At the beginning of the game, I always try to have the closest maid move it to the pool. That way I can direct people to the pool or they choose to use the pool themselves and they stay under for a period of time. Dinning Hall is probably another good place for it. But you want to put it somewhere you can gain some traffic constantly. Baths not really because its splits into genders.
Taser - As they search rooms,. items might pop up and be picked up by visitors. The taser is something that Katanahi and hte maids can use too. Its also dangerous to use against you. Its an instant incapacitate. This is the must confiscating item. Katanashi usually works best at confiscating. But maids can do ok too, or when the visitor is sleeping to avoid maid concern hits.
Body Swapping - This is only useful in two ways... But for one. Never body swap with a monster girl, I think its not working correctly where the monster girl will go hostile. More harm than good for its cost. Bodyswaping between maid and vistor is not advised either with the cost it takes, but I suppose it may be used in an emergency, but even then the cost isnt worth it. The usefulness of it, is body swaping traitors with other vistors to improve their statistics. It will cause a body swapping concern of the visitor and somewhat distraction, but the traitor has taken their stats and you lowered theirs. I think traitors accept this as their fate after having agreed to the deal of being spared. The other, body swaping two visitors is just mainly for a distraction and shits and giggles, but will cause them to start searching towards mysteries.
The Mirror - I havent fully tested this, sometimes it works, sometimes it doesnt. But its potential is to wipe the visitors mind and body. literally like resetting them as a new person with zero concerns. However sometimes it just be a body TF and the mind remains asif they just been body swapped. I think this is RNG based as I havent discovered further. Sometimes the mirror wont work and you see a mirror icon come up on the visitor stats. I am to beleive this is the countdown before the mirror can be used again on them. The mirror can be turn on and off and charged. Its description gives some idea how it works with charges. It can also work on incapacitated visitors even tho it clearly says that people need to look into the mirror (no sense right?)..... You can also adjust specific people you may want them to take after. I tend to like using the mirror to TG the males, but it doesnt always happen when its set as default random.
Arlunes and Front Yard - The Front yard seems to be the the place where people go the least. Only for exercising or leaving but they could just go to the rearyard for that too making it 50% less. Putting Arlunes you dont intend to use in the Front yard is probably the better option even tho they can hide just fine in the rearyard if you want them there instead. If you're undecided or do want to use them, always rear yard. It sees alot more traffic visitors might try to get the the shed, or come from the pool to the dinning room. Plant zombified are stupid, they come with a goal to reach Front or rear yard but get lost trying to get there Maids/Katanashi can guide plant zombies to the front or rear. Its also not shown, but they actually do scream for help when they start zombifying. Which is funny when the nearest visitor comes and asks them directly why they screamed for help only to get no response, then they leave and go back to their own concerns.
Also, sending a visitor whos infected by a seed, to the bath or pool actually does speed up the infection.. Who knew watering plants could have that effect ^_~
Master Suite - Katanashi actually gets a few good bonuses here. Not only is it the ideal place for instructing maids. Her direct transformation abilities are reduced cost. Instead of 150 for a full maid transformation, she can do it for 85 and 34 for trainee. Further, if the target is incapacitated and brought to the Master suite, its then 25 trainee and 62 Full maid. So dragging incapacitated back the master suite isnt such a bad idea to have them volunteer.
Library - You can select an option at the library where maids to recommend trap books. Trap books are the ones you create and just leave on the ground in hopes a visitor will pick it up to read. Otherwise you library maids will just try to recommend them decoy books that provide nothing useful. Alot of this is RNG based, so they still could end up with a useful book with some bad luck. Well this is from my observations, I dont see the stats.
I thought I had more, but thats all for now. Hope that gets a few people started on understanding the game.