Karen, I guess I got lucky, to a degree. I usually order through their web site, and I base my color choice on the swatches they show there. Since I'm a fairly serious photographer, all my computer monitors are calibrated to be as accurate as possible, so as long as Avon has taken care to make the color of their swatches accurate, I can get a fairly good idea of what the colors actually look like. Sometimes it doesn't work though and I end up with a color that I don't want, but not too often.
I used to have an Avon rep that I bought from, but she moved away and I haven't made the effort to find a new one. Being transgendered, I'm always a bit hesitant with stuff like that, as some people don't react well to someone like me.