I am going to make a real life horror aventure with friends! need help for scares!

[Skandis]

Opening the windows, leaving doors/cupboards half open and taking out the lights in most rooms help a lot. You want sound to create atmosphere, and wind is pretty dang good at doing that.

You could also lock down a room and let one of your agents find the key. Put fake blood on the bedsheets and let them dry before putting them back, create some tumult in the room, get a black marker and start writing some notes in the sense of "If this is a dream I wont see this note again" "Why is this happening!?" "Did I DO THIS".

Consider finding some story with the consensus that "Apparitions are spirits that only appear to those that feel they should be punished". If someone tells you to not think about polar bears, you're bound to do.

You could also take out the electricity pretty early on, if the fusebox isn't easy as hell to find. Your agents could've brought a few candles "in case of it". They could also claim that fiddling with it in a house like this would be pretty dang dangerous.

If possible, get a grammophone. It'll be epic.