Hair straightening irons that use heat and pressure to make hair look smooth should be avoided, according to Hamburg's star hair stylist Manfred Martz.

"Hair dryers are the secret," Martz said. Hair tends to hang limp after using a straightening iron, while blow drying smooth gives it a certain natural volume, he said.

Hair should be towel dried before starting to blow it dry. A large round brush and an attachment with a narrow opening should be used. The hair should not be rolled up in the brush, said Martz. Instead, it should be gently pulled through bristles while blowing it dry.

He also recommends using a spray or other product that protects the hair from heat. These can prevent dryness. A smoothing product also can help.

"You've still got to blow the hair dry. These products alone don't smooth the hair," Martz said. Don't be discouraged if you don't get it right on the first go, he added.

"It takes a bit of practice."