Don't assume that because you're a girl this is happening, although some may not recognize you as a customer right away. Most guys actually enjoy seeing women riders!
Some places the service just sucks. If you go to the counter and ask, and they still don't help you, then you did the only thing you can do. Ask other riders in your area who's good to deal with and try them. You'll eventually find a good shop.
By the way, welcome to the biking community, good luck!