Round It Out
Once you've got the right bristles, consider shape: A flat, vented brush is out when it comes to blowing your hair straight like Kate's. You want to use a round one.
A round, natural-bristle brush helps make hair look sleek. Wrap hair gently around the brush and pull it upward, with the air aimed at the brush (not the hair extending out of it). The result will be more natural-looking, bouncy straight hair, with an ever-so-slight wave.
And then, there are those pesky ends …