I want touseled hair (sp?!!) help, please!?

I want to do the tousled/slightly curly hair look, but my hair is sooo thick and heavy that it seems to be impossible, all curls and waves just come out after an hour or so, even when i drench it in hairspray! even my hairdreser said that it was impossible! but i was wondering i anyone out there has overcome this problem, and has any suggestions? thankouu!