Nicky Lazou pointed out that incorrectly covering grey hairs is "one of the biggest mistakes" she encounters in her profession.

When asked which colours to avoid to prevent looking older, Nicky revealed: "Going too light to cover grey hair is one of the biggest mistakes I see."

Nicky shared: "Most people think that to look younger, you need to hide the greys and go blonde." She elaborated: "Unless your hair is naturally light or blonde, highlighting too much or completely changing the colour of your hair to go significantly lighter can age you, especially if it clashes with your skin tone."

The hair guru also warned against the use of a single, flat colour for coverage. She advised: "If you want to stay darker but hide the greys, using one colour for the entirety of your hair can also age you as it draws attention to your eyes and cheekbones which can be indicative of ageing."

So what's the secret for women who wish to dye their hair and still look vibrant and young?

Nicky recommended: "I recommend incorporating another colour that’s one shade lighter on the strands around your face to help give you a youthful glow."

According to Nicky, there are numerous colours that can make you appear younger than blonde: caramels, honeys, golds, and strawberry tones.

"Caramel highlights can add a warm tone to your hair with added dimension and help give an impression of extra volume," said Nicky.

"If you really want to go a bit more blonde to cover some greys, a golden balayage is a great choice as it will also help you to stay closer to your natural colour and can be really flattering if used in a way to frame your face," she added.

Additionally, unhealthy strands of hair can also betray one's age, so the hair needs to be kept in good condition.

For those seeking to maintain youthful tresses, consider hair sunscreen to prevent sun damage which can fade its colour.

Alternatively, wear a hat under intense sunlight is advisable, especially on holiday. Another recommendation is to maintain a regular trim to keep your hair looking youthful.

By regularly removing split ends, the hair can look refreshed and well-groomed, which can only help you to look more youthful.