Get in contact with some local designers and spend time with them to get a feel for the industry. You learn a lot by spending time with someone who does what you aspire to be. Practice also makes perfect so get her to design a couple of things and have a mini fashion show to get her name out there. Start small at neighborhood functions and you'll eventually get noticed by the right people. If she then feels confident enough to approach a store to display a rail of her clothing she can get an idea as to who her client base would be.