HOUSTON, TX - Being able to defend yourself is a critical skill to have. If you're considering to learn how to fight back, this is a must-read.
1) Be aware of your surroundings. Attackers will often approach their victims, trying to play it innocent or to threaten you for money. This will mostly happen in a quiet place where you might expect people to be e.g. down the road at night. Keep an eye out for people who might approach you.
2) Hide. Fighting an individual should only be considered a last-resort method. Exhaust your options before you physically defend yourself. Remember that hiding will most likely trap you and put you in a vulnerable position if you are found, so maybe you should just fight them.
3) Assume a proper fighting stance if the assailant will not stop. Turn your body to the side so that your right shoulder [or left, depending on your dominant hand] is facing your attacker. Raise your fists into the air to protect your body -- not too high, so that you don't end up blocking your line of sight, but not too low as to offer no protection to your head.
4) Know how to block an attack. To block a punch, use an open hand and push the fist out of the way enough so that it does not hit you somewhere that it may cause damage, such as your head, stomach, or groin.
5) Know how to counterattack. From a fighting stance, a punch should come out from the center of your body. You will want your punch to come in quickly and return quickly -- don't leave your arm hanging out where the attacker can grab it. You can also kick to do damage. A kick should come from the foot that is back in the fighting stance. Or not, front kicks are often very effective as they don't leave you open for long.
6) Appear strong. Posture is everything: keep a straight back, fair walking pace (but not too fast or you'll appear suspicious and frightened), hold your head high and if you are particularly walking through a bad area, resist the urge to look away from those around you.