Here's my take on Korean fashion from my time in Hongdae (my gf is a Hongik student so I go there a lot): Wear some synthetic leather shoes, wear either horribly faded Buckaroos or extremely skinny jeans with no stacking, wear an obnoxious white tshirt. These are the basics. To make your style REALLY shine, add a HAT and VEST. Now you are the most stylish dude in Korea, just like everyone else. For that extra bit of style, wear some fake black plastic framed glasses. If you are a girl: look like a hot but naive prostitute. I don't really complain about how girls dress in Hongdae though.