Headband Curls! (one of the best No-Heat curl methods I have tried) -
This is a variation of the headband curl method by Oksana on The Long Hair Community. It's a no heat method to get beautiful spiral curls, while you sleep!
Go to this link ^ for Oksana's detailed picture tutorial.
Here are my results! Not bad for the 1st try. As with most no heat styling methods, it takes a few time to get it right. If you try it, don't give up if it's not perfect the 1st time! This should work for hair that is almost shoulder length or longer.