Use a shampoo and conditioner duo that seriously moisturizes hair. Not only do these products make your hair smooth and healthy, but they help to elongate your curls and prep them for heat styling. It helps to do a regular conditioning treatment every week too -- either a hot oil treatment or a store-bought hair mask -- because your hair needs extra hydration if you plan on straightening it often.
Squeeze some of the moisture out of your hair with a towel (don’t rub because this invokes frizz). Clip up most of your wet hair and leave the bottom down, then work a smoothing cream with heat protection through the wet hair to tame your curls and lock in moisture.
Blow-dry your first layer of hair in small sections, aiming down in the direction of your hair growth. Continue letting down new layers of hair and adding smoothing cream before drying. Straightening out the hair while you blow-dry is an essential step to prepping your hair for the flat iron -- if you tame it while it’s wet, it’ll respond way better to an iron.
Set your iron to the lowest heat setting that will do the job, then run the iron through ¼-inch sections of hair, starting with your bottom layer. Put as little pressure on your hair as possible when you clamp the iron on your hair, and twist your wrist slightly at the tips to curl the ends of your hair under. Using an anti-humidity spritz on dry hair before straightening may help with frizz, or you could use an anti-frizz flat iron to do the trick.
Continue smoothing your hair with the flat iron in small sections. When you reach the top layer, you may have difficulty smoothing the curls or waves closest to the roots. Remedy this by brushing back your part and inserting small sections on the top of your head into the iron. Run the iron from roots to tips, lifting the iron vertically above your head. Hint: A thinner curling iron with wide ceramic plates will do the best job of converting your curls to silk near the roots.
For ease of styling, use blowout spray on wet hair to smooth curls into a wave -- or have a mild relaxing treatment done at the salon. While strong chemical relaxers can seriously damage your hair, modern relaxers (those that convert tight curls to looser ones) are less harmful. Keratin treatments, which actually work best on processed hair, are chemical-free and can effectively loosen curls. On the down side, they wash out after several shampoos.