What kind of brush do you have? She may just not like the type.
No, I wouldn't persist with brushing her if she doesn't like it. It'll only make getting her used to it in the future harder.
Maybe practice petting her with your fingers straight down, kinda like the bristles on a brush.
Make sure you aren't brushing too hard, and start off with hand back massages and then slip in the brush with alternating hand/brush strokes.
I'd have some treats in your pocket for occasional reward as well. Soon enough, they should think its the most awesome thing ever and come running when you pull the brush out, I know these two do. They don't like their tummies brushed though.
I use a brush like this: http://pet.imageg.net/graphics/produ...-6979258dt.jpg. Her previous owner used one with metal bristles, which she didn't like. Sometimes, when I am approaching her, I have to hide the brush behind me and then whip it out when she isn't looking lol.
I have one who will not let me comb him-we've tried different combs and brushes-though he's long haired and a comb is a must. We've tried bribing with treats. He doesn't even like when we comb the other cats and swats us for that too. For now he just gets sedated and shaved every few months-he gets matted because we can't comb him.