When I walk I always watch behind me via windows, car reflections, shadows, sunglasses held to the side, or anything else. I try to maintain a 360 degree awareness at all times. I've found that this alone has put me in the ready quicker and constantly, far before anything else can happen. It give you the opportunity to react before people expect you to even start to process the information. I also don't get drunk in public without a large group. I'm too busy watching everything people do around me if it's just me, a buddy, or a lady friend. If someone is near me, my eyes are on them in some way, even if its just how i position myself.