I think it's foolish to buy someone clothes as a present, unless they've specifically told you what to buy. Honestly, in between sizing issues (yeah, I'd love to go exchange this present at the mall along with a million other people) and differences in taste, you're better off gifting straight cash yo.
That being said, if you absolutely have to buy fashion items, stick to a few basic rules: accessories are better than clothes, sweaters and other stretchy/loose items are better than structured items, chance on the side of too small if you're unsure of the recipient's size, and don't be offended if the person does return your gift (because she probably will).
