I haven't actually purchased very much from Etsy, but I can tell you the things that are likely to influence me to buy something. Bethalize made some really good points.
One thing I see a lot on Etsy are people who take pictures that are really not very good. Even aside from an artistic standpoint, they're dark, they're blurry, they don't really show the item in question fully. I don't want to buy anything that I haven't been able to see in person unless there have at least been some good pictures showing me the whole thing. So a close up of a necklace that only shows the front and a description of the back isn't going to cut it for me. I want to see the whole thing.
The other thing is that how artistic a picture of a product is really makes a difference. It doesn't make a huge difference, but if I'm comparing two similar products, and both of them have good quality pictures that show the product in various ways, I'm going to be more attracted to the product that has the more aesthetically pleasing pictures.
Finally, the description and the tags are really important. Etsy searches can turn up thousands of hits. And some people really don't tag their items very effectively, so they show up in categories where I wouldn't think to look at them. The description is really key, too, because that and the picture are all I have to go off of. I want dimensions, I want the size of any defining elements, I want colors, I want to know if you're open to customizing that piece. But perhaps most importantly, I want to know why you think I should buy it for the price you've set. Not because you say it's high quality or unique or anything else like that -- give me definite, measurable reasons (like telling me you use real gold or something). Tell me what distinguishes it from the cheaper options, even if you think it should be obvious from the picture.
That's all advice you can give your friend, but I don't think you should tell her she's charging too much. There's really not much point in attempting to sell handicrafts if you can't pay for the materials and a decent profit. Some people like to sell stuff like that simply to sustain the hobby (so they're basically discounting the cost of their own labor and selling it for the cost of materials), but that doesn't mean that someone who is including a profit margin is charging too much.