What is the crucial decision on the mind of most teenage girls right now? Shoes. Back-to-school shoes, more specifically. According to ElleGirl Magazine, it’s all about sneakers. There are so many styles of trendy canvas footwear out there, you probably need help deciding. The magazine has an online back-to-school shoe gallery, but here are the highlights: Vans, Chuck Taylors, Reeboks, Nikes, Pumas, Coach, on and on . . . they all have wildly colorful variations on the sneaker theme. Here’s a pair worth pondering: Reebok’s Freestyle Hi Basquiat Classics for $199.99. Don’t worry, though: The old standards are cheaper, yet still stylish. Hilary Duff has been seen trotting about in her old black Chuck Taylors, and Mischa Barton was recently padding around in plain white Keds.