Handling wet hair will make it frizz in a flash so it’s best to implement waves on dry hair.  Petra Ecclestone has long, all-one-length hair that will weigh down a style, however, you can still get a little bit of wave like she has by rolling up completely dry hair, pinning it, apply heat from a dryer, completely cool (preferably with the cool setting on that dryer), take down and watch the magic unfold.