How to get perfect wavy hair?

how can i get perfect wavy tousled hair like vanessa hudgens and miley cyrus...ive tried to replicate their look but it always looks to polished and styled for my taste so what can i do to change that. i dont have a large curling iron i have a conair infiniti curler, it doesnt have a clamp, and i could also use my straightener...i have medium length thick hair if that helps