To be honest, there never was style. I've always seen the cowboy and cowgirl deal as sort of for the type who rides horses and owns a stable, or does some heavy-duty work in a ranch. Outside of that, this is as worse than tucking pants into boots. I'm not the cowboy type. Don't assume that just because I'm from Texas, that I have a ranch or some cattle. I've been so over this American Western deal, especially that of cowgirls. The farthest I've seen most girls go is just wear a T-shirt with some sort of American Western theme, and that's it. I don't really see cowgirl boots, the cowgirl hat (unless you're part of the Tejano community here, who usually are active in western-style fashion), or anything like that. This has presumably been another call to attention, much like the ladies who claim to be surfing divas. I can get used to the surfing trend, but the cowgirl stuff has to go.
I'd probably recommend a unique cowgirl or western look with a specially-paterned button-down shirt, some comfortable (not glamourous or trendy) jeans, and find a nice hat. Go with the cowgirl deal if you wish. Just be sure to LOOK the part of a cowgirl than just pretend to be one. If not, the whole deal is dead. Can you dig that?