Keira Knightley avoids foundation due to past bad skin. (Pic: Reuters)

British actress Keira Knightley has revealed her top beauty tip for keeping her skin fresh looking is to avoid wearing foundation.

After suffering from "really bad" skin up to the age of 24, the British actress prefers a minimal makeup routine to allow her skin to have a break when she isn't filming, and admitted that her motto is "less is always more" when it comes to the products she uses.

Speaking to Vogue.co.uk, she said: "In the mornings I use a moisturiser and then just concealer, never a foundation. I like to see skin through make-up, so I think less is always more."

The 'Collateral Beauty' star has also explained how she tried "everything under the sun" to help find a solution to her problem skin, but after it cleared up, she was reluctant to pile on the make-up. 

Keira, 32, said: "I had really bad skin until I was 24 and up until then I did everything under the sun to it. Then one day I thought I would try to leave it and that's what suited it better. That's also why I always want to wear as little makeup as possible when I am not working. When I'm filming, I always have a breakout as we have to cake the make-up on. I think it needs a break every now and again to be able to breathe."

When it comes to makeup looks she does like, Keira is "100 per cent more of a smoky eye girl than a lip girl" but revealed her mother's advice to feel confident in an instant is to put on some bold red lipstick.

She shared: "My mother always said, 'Lipstick is for when you've had a sh*t day and you need red lipstick to face the world.' I think it's really true. The other day, I had to get straight off a flight to get to a premiere. I wasn't feeling great, and I thought: yes, this is a red lipstick moment." 

The natural beauty - who is currently filming Disney's 'The Nutcracker' remake - is just "so low maintenance" and hardly ever treats herself to a manicure when she isn't filming. 

She explained: "If I am not wearing nail varnish, it normally signifies that I am not filming, so I like to do a really crazy colour as soon as I wrap. But I was just on a re-shoot for The Nutcracker and I had such crazy pink sparkly nails, that actually the treat was getting the nail varnish off! But normally it's the other way around."