no need to spend hours tryinig to get the 'just-rolled-out-of-bed' look. it's called that for a reason :) so help it live up to it's name and get this effortless style :)
-after washing your hair towel dry it & put it into loose plaits
-if your hair is quite frizzy use a serum or smoothing balm before you plait your hair
-leave in over night
-when you take the plaits out the next morning, run your fingers through you hair
-if you want use wax/gel/hairspray to pick out certain waves for a more textured look
if your not happy with your look (but i bet you will be!) throw in plaits anywhere you need to, or put it up into a messy bun with plaits either side or around the top.
good luck & have fun