tousled waves...HELP!

I have to say looking at the picture that there is no way that look was an air-dried contrived hairstyle. She definitely looked like someone with thin, fine hair that was blow-dried and then had product scrunched into the hair to make that tousled effect (especially the bangs and top). If you have hair like that girl, you can achieve the same look by blow drying on a low heat setting and scrunching something like styling gel into the hair before and after drying.
If you like the beach-look though, one trick I have tried is to dissolve some epsom salt in some distilled water (doesn't take much depending on your spray bottle), and spray and scrunch you hair to dampen it. This technique can really give a beachy, wavy look. I used it when in the Caymens to get the look without even getting my head wet in the ocean. Of course, I looked like I did so my secret was safe.
I should say that I have thick hair that is wavy in natural. I use to try to straighten my hair as well, but I am now embracing my waves. So no more straightening irons or even blow driers for me; my hair loves me so much more.