So should we not pet her at all and just force her to play with toys?
Is she biting you when you're strictly petting her? If so the problem is a different one. First of all you need to figure out if she's really playing, or if she's warning you because she finds petting to be disagreeable. Many cats become
overstimulated if petted for a long time (with "long" varying a lot from cat to cat), causing them to feel further petting as actually painful, and lash out defensively. With their owners, they will often first warn them by biting gently. If this is the case, then you indeed need to pet her for shorter periods of time.
On the other hand, if she's actually playing, you still need to teach her that hands are not toys. The best way to do this is to watch out for when she's going to start playing with your hands, then gently but firmly tell her "no" (or "shush" her) and pull back your hand. You can also redirect play towards a toy at this time. Once she's tired from playing, you can try petting her again. This will probably be confusing for her at first, but it should eventually get the point across that hands are for petting and not for playing.
Be sure to let me know how this all goes. :)