Reddit mentions of Defensive Living: Preserving Your Personal Safety through Awareness, Attitude and Armed Action

I would think that really important things to learn first would be proper situational awareness, and learning how to avoid things before they become problems, and learning how to run. I think a great cardio routine and the ability to put it in full gear with a sprint would be a great too. And then having the endurance to outrun your attacker. If you have to engage I think having a weapon on you (legal in your state) could even the odds, yet be sure you practice with that weapon and use it in a way where it can't be turned against you. Practice reaching for it too and pulling it out, and then be prepared to run afterwards. If you can't do that and somehow you still get taken into the fight then I would recommend BJJ, which will help you permit someone's bodyweight to go in the direction you want it to more and give you more of a fighting chance off the ground, and also Judo so you can help trip larger opponents (and then run). If you have to strike I would recommend something that has live sparring like boxing, kickboxing, or certain forms of karate, just so you get used to being hit and figure out the spacing needed for combat. Once you get used to that you'll be able to fight easier, and then run. And if you can practice going from one thing to the other, from striking to grappling. and vice-versa. Also learn to use your voice, and your posture, be assertive. Sometimes being direct but non-confrontational with people, (is there something I can do for you?) letting them know that you see them in a confident tone with direct but non threatening eye contact can let people know that you see them and maybe make them think twice.

I would recommend some books

Defensive Living: Preserving Your Personal Safety through Awareness, Attitude and Armed Action

The Gift of Fear and Other Survival Signals that Protect Us From Violence

Solo Training 2: The Martial Artist's Guide to Building the Core for Stronger, Faster, and More Effective Grappling, Kicking, and Punching (there are some great tips in here for the mental side of the game too, including tips for women)

Good luck with everything.

Also there's a great DVD set How to Defeat the Bigger Stronger Opponent with Brazilian Jiu-Jitsu

And Frank Shamrock has a good series on Defending the takedown Avoiding Takedown is Simple Part 1/3 (this one's on youtube Edit: Warning at some point there's some crackling in the right ear, be careful if you're on headphones)

Good luck!