For those that need a strategy quick, This post will have some basics.

You need some techniques for all three basic ranges: standup striking, in close, and ground.
-standup= Basically some boxing with a few kicks: jab, cross, hook, straight kick, and a round kick
-in close= clench, elbows, and takedowns.
-ground= basic positions, basic submissions, and escapes.

This is about as basic as self defense can be.  This only works for hand to hand and has little effectiveness against multiple opponents.  But It is better than nothing. With this, you increase your chances of success and It can be learned in about an hour easilly.  Remember you are not looking for perfection here, just something to keep you alive.

The good thing about today's society:  We have access to the world.  You can find this information easily by going to youtube.  So look up some basic boxing, in close fighting, and basic groundfightng.  You will be well on your way to being able to defend yourself