Self-defense is a very big part of being equipped to survive. Although my campus, like many, doesn't allow the possession of firearms on campus, I'm working on getting my concealed carry permit. So I will be able to carry in places where I feel the threat is great enough to justify carrying.

After that I think mace or another less lethal weapon is a good choice. Even (maybe especially) if you are carrying a sidearm, less lethal options should be considered. There are situations which don't call for deadly force, but can't be resolved peacefully.

Finally, if you aren't taking a martial arts, I think one of the best sources for unarmed combat skills is Colonel Rex Applegate's book Kill or Get Killed. Kill or Get Killed is availible online in PDF for free here . It's fairly old (1943), but it was written from his experiance training commandos in World War II. He doesn't teach very many complicated moves (a few of the throws are), just brutally effective, simple techniques for destroying an attacker. Its not a substitute for taking a martial art, but it does show you concepts that can be effective with very little training.

And like a couple people have already said, the base layer of any defense is awareness. I think its also one of the hardest skills to develop. I try very hard to stay aware of my surroundings, but I still find myself losing focus or drifting off into my own thoughts. Its something that has to be constantly practiced.