I'm thinking of picking up the Bebe Button-Up Sash Top from the recent blog post; this will be my first blouse, I think, they're not usually my thing but I love the tonal stripes and long cuffs. I'd like some advice on size, and thoughts on whether to get black or white (leaning towards black). What measurements do you need to know to suggest a size for me? Their sizing chart doesn't seem to work with my brain, but so far I'm guessing I'll be a Medium.