Re: When entering a room.
I used to be one of those 'bowed head' types. When I saw one of my friends walking down the street in a similar fashion and found myself thinking, "my God, they look like a victim," I decided to change.
Now I look at people. Never in their eyes, though. Just off to the side a bit. Or maybe at some area around their cheek or ear. Looking people in the eye always came off as too confrontational, I found.
Of course, I always just choose another street if someone looks a bit dubious. I also find myself judging danger by what people have with them. Anyone with a dog, pushchair or shopping, for example, will probably be preoccupied to start anything even if normally they might take a fancy to knifing me.