If you have particularly thick or long hair, you'll probably struggle to get a DIY curl to stay in. The longer your hair gets, the heavier it is and the harder it'll be to get a uniform curl to stay. You may find the ends go frizzy and curly, but the lengths fall flat. You have a few options to fix this. Firstly, get lots of layers chopped in, especially around the front, to reduce weight and give the hair some bounce. You should find that these shorter sections curl better. Secondly, chop your hair a few inches shorter. The simple truth is super long hair will not curl easily if it's naturally straight. Finally, if you can't bear to face the scissors, try twisting wet hair into a bun (or two buns for very thick hair) and sleeping on it, or try headband curls; dampen your hair, part it as usual, and put a narrow stretchy headband over your head so it sits halfway down your forehead and quite high at the back of the head. Starting from the front, take a section of hair from below and wind it up and round the band over and over again, adding more hair each time as you move around the head (as if you're creating a big croissant with your hair). Leave this in for as long as possible, overnight is best. When you pull out the band, your hair will sit in bouncy, full curls!