---> Plaiting hair to create waves... I need tips! Help (pics included)?

I want to acheive a look like this - a href="http://www.olsen-twins-news.com/newsimages/july-2007/mary-kate-olsen-weeds-showtime-tca-press-conference-july-14-2007-01.jpg" rel="nofollow"http://www.olsen-twins-news.com/newsimag…/a - and have tried scrunching my hair with mousse etc, but the waves are too big. I've heard plaiting my hair then leaving it overnight will get a look like this, but I've tried so many times before and my hair ends up a huge, frizzy mess, with no waves or volume at the top then harsh waves beginning halfway down my head! I need help lol! Any tips? ♥ x