I am brunette, and I have long, straight hair with a tendency to wave if not blow dried. I would love to get this wavy hairstyle (http://bp2.blogger.com/_uuReujh9X4U/Ry_jpyK2VGI/AAAAAAAAA8M/eWeIiHQVYaM/s1600-h/hilary-duff-fhm-photoshoot-05.jpg) as well as the hair color. Any tips for me?
Thank you in advance. :)

Blow dry it with a round brush... the kind with holes in it that you blow the hot air into to make it heat up and act kind of like a curling iron. You should be able to find this kind of brush easily. They probably used mousse or some other hair product to make it separate like that too.