How to Make Your Curls Stay
Tip #1: Change the State
The best way to make a curl stay in hair that is not naturally curly is to change the state of the hair as you curl; do this by going from wet to dry or from hot to cold. A wet set is more gentle and will always last the longest as the hair dries in shape. To do a wet set, wash and towel-dry hair, add your chosen holding product, then create your curls either with velcro rollers, your fingers and clips, rags, or bendy rollers (don't use heated tools on wet hair). Let the hair dry completely before removing. For quicker results, going from hot to cold will have the same effect, using hot rollers, steam rollers, curling iron, flatiron, or something similar.
Tip #2: Use Product, Always
When you're trying to get your hair to do something it doesn't naturally do, you need to give it a helping hand. Don't expect a curling iron or GHD flatiron to work miracles on its own. Use some product! Firstly, for hot tools you'll need a heat protector like L'Oreal Paris Studio Pro Heat It Hot & Curl Heat Spray. Then choose a holding product that will give added oomph.
If your hair has a natural wave, a curl-enhancing mousse like Schwarzkopf Got2Be Twisted Curl Mousse will help to provide hold and lasting power. But if you have straight hair, you'll need something really powerful. Superdrug Setting Lotion Extra Firm is like liquid hair spray. It's not the most glamorous product, but it will definitely help to hold a curl.