You can curl your hair using curling tongs or traditional rollers. One way to hold your curls is to mousse your hair before you curl it; this is especially effective when using traditional rollers. Simply collect a section of hair, mousse it with a good quality, strong hold mousse and roll. While it's in the roller, finish it off with a spray of strong hold hair spray and repeat until all areas you'd like to be curly are rolled. Leave them for as long as you possibly can and then unroll gently. Make sure you finish off with a generous spray of hair spray when all rollers are out.
Dry hair can really help your curls hold, and this method really helps very straight hair stay in a curly form. Make sure your hair is completely bone dry and then gradually roll in hot rollers. Once the rollers are all fixed in, make sure you leave them in overnight. In the morning, release all of your curls and spray with hair spray.
Squeaky clean and dry hair can really help hold your curls and to make it at its driest, make sure you use no conditioner when you wash your hair. Then, let it dry naturally without blow drying or handling it too much as this contributes to oils being released. Tightly curl the hair with hot rollers or around curling tongs (leave for 30 seconds if using tongs) and then release. Only use small amounts of hair at a time.