The 6 biggest mistakes guys make with their skin, according to the cofounder of a leading skincare brand

"Men are shaving less but when they do shave I think men are tempted to stretch out how long they take between changing their razor blades," Duffy says.

He adds that nobody should be shaving with a cheap razor: "If you are going to shave, make sure you're using proper equipment."

Failure to change your blades regularly will result in blunt blades and an uncomfortable, hair-wrenching shave.

If you do grow out your beard, it's important to keep it clean and well-maintained.

"Beard's just get so dirty," Duffy says. "If you think about how much you're running your fingers through your beard throughout the day, anything you get on your fingers is going in your beard."

In 2015, a swab analysis conducted by ABC-affiliated station KOAT found that some beards had levels of bacteria" comparable to toilets."

To tackle this, Duffy advises using a proper beard shampoo whenever you wash the rest of your hair.

Washing your beard is a great start, but if you really want to double down on your facial hair, it's important to style as well as clean your beard.

"You can tame an unruly beard if you need to be smart for the office with a balm or an oil," Duffy says.

With so much attention paid to styling the top of our heads, why not the bottom too?

Duffy advises beard-growers to buy a razor with a precision trimmer, "so you can get really neat lines."

He adds: "[Precision trimmers] will actually really help make something that might look quite scruffy look quite smart and you can accentuate the natural features of your face to the advantage of your look."

This is one of the biggest mistakes guys can make in their skincare routines, according to Duffy — and that's because of a key ingredient.

"Naturally-formulated shower gels are dodging an ingredient called SLS (sodium lauryl sulphate) — that is a really cheap foaming agent," he says.

However, he adds that it's found in a lot of more common shower gels.

"This foam is often mistaken for a feeling of actually cleaning you but... it's actually more for the experience than the efficacy of cleaning," he says.

Instead, Duffy recommends buying a proper cleanser that's designed for your face.

There's really no excuse to be using toothpaste on your breakouts anymore.

"Use a proper blemish targeter," Duffy says. "You're really looking for AHAs (Alpha Hydroxy Acids) or witch hazel, which would be a great natural ingredient for spots."