The poet Carl Perkins once wrote: "Do anything that you want to do, but uh-uh, honey, lay off of my shoes". Rockabilly king Carl's were blue suede, which is both hard to match to your outfit and a bugger to clean, but the general principle is very sound. Shoes are important. Bargain shoes in a sale? Even more so. And so we turn to resident shoe guru (shoe-ru?) James Welsh, of the ASOS Personal Stylist team, for his insider tips on how to pick out the best kicks.