There is one tip about self-defense that is so important that entire martial arts systems are based upon it. 

Don't get hit!

Moving along a triangle goes a long way toward achieving the goal of not getting hit. One of the most dangerous mistakes the average person makes during a fight is to move in straight lines. They will move in a straight line, either forward and backward, or side to side. 

The aggressor is probably going to attack some point along or around that line: your face, your throat, your heart, your groin. Moving in a straight line backward or forward will change the distance you are from your attacker, but it does not move your centerline out of the attack path. Moving laterally (left or right) will change the location of your centerline, but it does not change the distance between you and your attacker.