Washing your hair for three minutes will help ensure its long-term health, according to trichologist Frank Cunningham.

"Wash your hair for less time," he says, "and you risk leaving in much of the shampoo, which can give you a flaky scalp."

Before you turn on the shower, brush your hair with a wide-tooth comb to prevent tangles; then wet your hair, and apply shampoo. "Use a clawlike movement, rather than a flat hand," Cunningham says, "and if your hair's long, don't apply the shampoo directly to the ends – lift the length of the hair and squeeze the crown so that the shampoo flows down to it."

Once you've rinsed out the shampoo, it's time to apply conditioner – but, Cunningham warns, "don't apply the conditioner to the roots – only to the ends – and make sure you don't rub your hair. That can cause splitting."

Then rinse your hair until the water runs clear, and comb out any tangles using the same wide-tooth comb – never a plastic brush. "If you saw a brush under a microscope," Cunningham says, "you'd see that its bristles act like a saw. You really have to watch what you're doing, especially with long hair. I always tell my clients that they should treat long hair as they would a silk blouse – extremely carefully."

• Frank Cunningham is a trichologist based in Ashton-under-Lyne, and a member of the Institute of Trichologists; trichology.co.uk