Re: The Sixth Sense
Our sensei sometimes during ki breathing practice suggests we extend our ki all around us. And also during the "warming-up" excercises (sorry, don't know the name for that). Somewhere I remember reading that while riding on the bus or walking or meditating and simultaneously picturing images of the scenery behind your back in as much detail as possible is good awareness practice.
I wouldn't really suggest seeing every situation as potentially dangerous and anticipating an attack from every person that walks by. That would probably make you paranoid, plus your mind would constantly be under pressure, fixed on an idea of someone attacking you. To me, that isn't a relaxed mind.
Thoughts are energy and they also travel well through space. To me it's not uncommon to, say, get a phonecall from a person I'm just thinking about. Not to mention feeling my partner's emotional state sometimes without words or eye-contact ever being made. And I am absolutely convinced that this is only a starting point from which further expansion of awareness (or intuition or 6th sense or whatever) is possible.
By "tuning-in" to people it's easier to feel what they're up to. You can feel their intention. By my experience, the closer a person is to you (both physically and/or emotionally, e.g. your partner, brother, friend...) the easier it is to "feel" them. So they're also the starting ground for my training in awareness.
Aditionally, I believe that opening yourself to other people (by being nice, non-egotistical, etc.) thus making them closer to you also makes it easier for you to sense the nature of their intention (as I have mentioned above). Perhaps that is another reason why we should somehow start to percieve ourselves as a tiny part of the Universe, just like every other person, plant or animal we meet.