Great advice by all!
I would even further reinforce a few points made-
1) don't throw toys at or near a cat with a suspected abused past. You definitely want the toys to have good things associated with them. I'd also avoid battery operated toys like Panic Mouse, which has pieces tha whip around and again, can make playtime scary.
2) Everyone has mentioned the stuffed mice and I third the motion! Helping your cat self-start her hunting instinct, and hopefully being in a position to then praise her for it can be a key in her behavioral development.
My favorite all time toy is Da Bird, which is the classic feather on a string toy, but the feather swivels so that it makes the sound of flapping wings when it flies around. Yay! Not that you'd make it fly around for your scared one at first. That's the great thing about it. The cat can learn to trust an interactive toy like this slowly, dragging on the ground as someone else alluded to, and eventually moving into more frenetic gestures more resembling prey. The great thing is that you are attached to the other end of that toy, encouraging the whole time and making sure it's always a positive experience.
You may want to be careful on the catnip front-just remember that all cats are unique as they respond to catnip, some having very adverse responses. Point being, that instead of having that picture of a zoned out happy cat rolling around with her toy, 10-15% can actually have the opposite response, some becoming more on guard or even borderline aggressive. Just something to watch out for.