I travel to WDW solo often, I'm gray haired and a smallish woman. I always put the chain or equivalent of it on the door if I'm in the room (I do that no matter where I'm staying even if hubby or my grown son is with me). I don't usually put the room occupied sign on the door unless I know I'm going to be in the shower. I've been pretty lucky I guess. Usually when they knock on the door I look out the window if there is one or open the door a crack with the chain on or look out the peephole if there is one, just to verify there is a name tag. I've opened the door and been told they were just checking and asked if they need to come in the room, they just sort of peek around me and say no that's fine. I've never had one actually step into my room while I was there. Now what they do when I'm not there I don't know. I do put my wallet and car keys and laptop in the safe (if it fits) every time I leave the room. My wallet and keys stay in there and the laptop just goes in when I leave the room. If my laptop doesn't fit, I either put it in my dirty clothes drawer under the sweaty clothes or in a suitcase in the closet with something on top of it.