I used this recipe, which is great because it contains nourishing coconut oil to protect from the dryness of the salt. It should only take about five minutes to mix up the spray, and I can vouch for the fact that it really does work!
You'll need: An empty spray bottle, 1 cup of warm water (to help the other ingredients dissolve), 1 teaspoon of coconut oil (I used this one), 1 teaspoon of sea salt and 1/2 teaspoon of hair gel (I used this one) for hold. If you have especially thick or really straight hair, add a little extra salt. You can also add essential oils or a tiny drop of your favorite fragrance if you want the spray to be scented.
Spray it on damp, towel-tried hair and scrunch hair with your fingers to build waves. If you want more defined curls, touch up with a curling iron (or flat iron!) once your hair is dry.