The trick to a perfect bun like Lauren Conrad's? A foam hair insert like the one from ASOS ($9; asos.com). They take the guesswork out of forming an ample updoall you have to do is roll them into place. Conrad's hairstylist Kristin Ess split her hair into three sections, then rolled a straight-line hair foundation into the back to create her bun. "Drape the two side sections over your bun, and if you need to, wrap them around a curling iron first so they blend seamlessly," Ess said. And don't skimp on the bobby pins; since the foundation adds weight to the style, use more hair pins for extra support.