Deterrence is one of the important aspects of street defense. First you try to avoid situations. If you can not avoid a situation then you try to deter it. If you cannot deter it then end it as fast as possible.
Part of deterrence is showing that I am ready able and willing to put up a serious fight in order to defend myself. This can be done using your eyes, voice and body motion.
Your eyes need to be focused either through them or on their forehead between their eyes. Your voice should be loud and direct with commanding tones of “Get Back” or “NO’ etc. Your body motion (not stationary) should be similar to how you can fight and also keep the attacker at a distance.
Clear’s Silat Welcoming postures are very good for this. They tend to convey non-verbal body language that is easily understood as “Stay back, I don’t want to fight” while also creating a barrier between you and the attacker. This kind of positioning done correctly also makes it easy for you to walk or run away if there is an opportunity to do so.