PrettyLoaded.org notes the "Force Multiplier are the tools or skills that enhance force you are able to provide in response to an attack." Skills are Self Defense moves that you can utilize while tools are the Defensive Hardware.
The first rule for any of these is of course proper training and then practice, practice, practice. Your self Defense tools / skills are very personal in that what do you feel comfortable with using? Other considerations are what does your state allow you to carry? Some states do not even allow Pepper Spray so you must do research before you purchase your tool (maybe that should actually be rule #1 for defensive hardware).
I encourage everyone to go to a gym or to their local police or sheriff's dept. to learn more about available self defense classes. This will be the best way for most people to learn these moves. Another option (if no one is teaching locally) is to watch self defense moves on YouTube and practice them at home.
Also, remember physical fitness plays a part in this as well. "Strong is the new skinny" and you do need a certain level of physical fitness to defend yourself against an attack. So, like many others, I myself need to be hitting the gym! Let's go pump some iron :).
We will talk about Defensive Hardware in another segment! Stay tuned for future publications.