WHEN Angelina Jolie hit the red carpet for the premiere of “A Mighty Heart” last week wearing a $26 dress from Los Angeles vintage store Wasteland paired with $600-plus Christian Louboutin heels, it was official: High/low is having a moment. Saavy shoppers and celebs alike have caught on to the stylist secret of mixing high-end designer items with cheaper pieces, be they a flea-market vintage find or a fast fashion fix from Zara. Merchandise at chain stores has become so good in terms of styling, and in some cases quality, you just can’t pass it up. Now when you see paparazzi pictures of Beyoncé or Lauren Conrad, chances are you’ll recognize the H&M or Forever 21 dress with the Chanel bags and Dior glasses. But it’s not as effortless as Angelina makes it seem. We asked five New York women to help demonstrate the trend and the rules you need to follow to pull off a fabulous high/low look. PRISCILLA Freelance stylist 1 ONE MAN’S JUNK IS ANOTHER...