Women of races that are different from the locals in Cairo tend to attract attention and consequently, they face a lot of harassment.
Consider asking your male friends, colleagues or partner to accompany you when going out and if none is around wear a ring on your wedding finger, married women are more respected and quite feared compared to single women hence face less harassment. In case you forget to put on the ring, should anyone ask you if you're married say yes regardless of your marital status.
If you're alone, avoid walking on streets which have groups of boys and men hanging around. Frequently, they try to call you to come over, pinch you or even touch you.
Should anyone touch you stand your ground, be firm and yell loudly at them, that will scare them away.
However, there are very few cases of sexual assault that are heard of so it's quite safe though you need to be on high alert.
Your best option is to visit with female friends or a male colleague, friend or partner