Never move in a straight line forward or back. If you are moving forward when approaching a suspect, step to his right or left shoulder. Never come straight in. This makes you a less direct target if he chooses to attack.
If you are getting attacked, move “off line” (or, as DT instructor Gary Klugiewicz would say “get off the tracks to avoid the incoming train”) so that the suspect has to redirect his movement before he or she is able to continue their attack and get to you.