To get this Bella hair look, use a medium barreled curling iron to curl your hair in sections. Take two small sections of hair from the front, loosely twist them them and pin them back with bobby pins.
Pre-Joan Jett mullet haircut, Kristen had great hair (who knew?). To get this look begin with wavy hair if possible. Add in extra curl by wrapping two inch strands around the barrel of the curling iron without using the clamp. Finish with a cream such as Bumbles and Bumble Grooming Creme to give it a more piecy look.
If you have a pixie cut like Alice, use reworkable styling putty like Shu Umeura Art of Hair Shape Paste on the ends of your hair. Use a flat iron to straighten your hair and make the ends flip up and out.
In real life, Ashley has a take on the bob: a little below her chin with a few layers in the front. Use a serum to cut down on fly-aways such as John Frieda Frizz-Ease Serum. Blow dry or flat iron your hair strait.
Rosalie's hair is very achievable. Beginning with straight hair, use a large barrel curling iron to give yourself some loose curls on the lower half of your hair. If you want some extra hold, try Tresemme 24-Hour Body Root Boosting Spray.
Nikki has long hair with some long layers in the front. If you have naturally straight hair you can simply blow dry as usual and finish with a flat iron for a more polished look. Wavy hair may take a little more work with the flat iron. Finish with a spray such as Citre Shine Shine Mist.