Here are some techniques you can use to defend yourself.
Break Falls-Learning break falls will prevent you from being injured if you are thrown hard on the ground.
Weapon Defenses-You need to know how to defend yourself against weapons. You never know when someone will pull out a gun/knife.
Chokes-It is great to learn choking techniques because a choke can be executed form the front or from behind and is very hard to escape from if you do not know the proper techniques.
Strikes-Learning basic strikes such as palm strikes and leg kicks are great because they are simple to learn and are what you need to fight off an attacker.