#1 thing is WIN WIN WIN and race at different tracks, try to hit the entire local schedule (race every day of the week if possible) and if you place in the top 10 or so of the regional standings you just may get one. I picked one up in my racing days after my first season coming in at 14th in the regional standings but it only scored me a 10% shop discount and they wanted me to ride their jersey, which I had to pay (alot) for. It was a start though
An easy way is to grow some tits - sponsors have a much more open policy for girls who ride.
Now, I know that sounds gay, but it is just a simple reality that the girls that ride, even the good ones, aren't nearly as good as the unsponsored male riders... I also have a ton of respect for girls who ride. I also think it is GOOD that sponsors are giving girls some support. But, there are very few girls who can hold their own on the dance floor and none would be likely to break top ten in the expert class.
I'm rooting for Nena though.
EDIT: Oh, and Erin Dinato kicks the butts of many in flatland. Much respect and props.