20 beauty tips that will never go out of style, from beauty experts who've seen (and tried) it all.

Want to support independent women's media? Become a Mamamia subscriber and get an all-access pass to everything we make, including exclusive podcasts, articles, videos and our exercise app, MOVE.

When it comes to beauty advice, there are two women we trust with our whole heart (and our whole face): Leigh Campbell and Kelly McCarren.

Between them, the You Beauty co-hosts and beauty experts have tested hundreds (possibly thousands) of products, tools, treatments and trends over their many years in the beauty trenches.

They've seen it all, tried it all, and know exactly what's worth your money… and what you can skip.

So naturally, we asked them to spill their best beauty tips of all time.

Thank you, Leigh and Kelly!

WATCH: Wait, are teens driving higher beauty prices?! Post continues below.

Leigh and Kelly's best beauty tips.

Tip 1: Ditch the one-off facial.

"Booking a random one-off facial is kind of like going to the gym once," Kelly said. "There's just not much of a point. Sure, you'll get a bit of glow, but that's about it."

If you've got a couple of hundred dollars to spend, she said you're better off putting that money into a hardworking serum (or two) instead.

"Consistency is key… the facials that actually change your skin need a minimum of three, and that gets expensive. Save your pennies unless you're going for relaxation vibes. And if you want that, get a massage, then spend the rest on a serum."

Tip 2: Your foundation lid is secretly a concealer.

You know that tacky, thick product that gathers around your foundation pump or lid? Don't wipe it away.

"That is the most perfect concealer because it's the exact same shade, just thicker," Leigh revealed. "Use it for spots or under the eyes, it's literally a two-in-one."

Tip 3: Dial down the fragrance.

If you're heading into an enclosed or small space, Kelly begs you to go easy on the perfume.

"Perfume is meant to be enjoyed, not overpower people, and people just don't realise how offensive it is. Please don't, for the love of other people… It is much better to use a little bit and have just a little waft. People shouldn't be able to smell you if they're a meter away from you."

Tip 4: Natural deodorant is not 'better'.

"If you are on this seemingly endless hunt for a good and effective natural deodorant and you can't find it, stop and go back to the regular deodorant or even the clinical deodorant because it is a myth that natural deodorant is better for you," Leigh said.

"Regular clinical aluminium deodorant is completely fine, completely safe if you check all the studies."

Her go-tos are Rexona, Dove and Mitchum because they're fuss-free, affordable and effective.

Tip 5: You don't need a million products.

Just because someone raves about a product doesn't mean you need it.

"Don't listen to a podcast or see someone on Instagram talking about a product and think, ah, I must have that," Kelly said.

"The point of being influenced or recommended something is that if you need a product within that category, or you are looking for something new, then that is a good recommendation to take on board."

"If you already have a hydrating serum that's working wonders in your routine, but then we talk about one, you don't need to go buy it. In fact, please don't, because it's just gonna confuse your skin and the other one's probably gonna go to waste."

Pro tip: Keep a Notes app list of recommendations and only buy something when you run out of that category.

Tip 6: Applying hair masks to soaking wet hair is pointless.

Most hair masks say to towel-dry before applying, wait a bit and then step back into the shower to wash it off. But let's be honest, who can be bothered doing that?? Not us, that's for sure. And thankfully, Leigh has a hack.

"I do want you to step away from the shower stream and squeeze as much water out as you can" before applying your hair mask or conditioner."

There is a method to this madness:

"Picture your hair, a hair strand is like a glass of water. If it is full of water from the shower, you can't pour more water in. So if you squeeze as much out as you can, then apply your mask or conditioner, it can get in."

Tip 7: A good base is the key to flawless makeup!

Every makeup artist will tell you the same thing: good makeup starts with good skin prep.

"Please prep your skin properly if you want your makeup to look glossy, glowy and last all day," Kelly says.

Prep looks different for everyone: shaving peach fuzz, using a sheet mask, or massaging in an oil or serum.

"It sounds so small, but the difference is astronomical."

Tip 8: Oily skin might be dehydrated skin in disguise.

If you're stripping your skin with astringents to fix oiliness, you might be making it worse.

Oily skin can be "circumstantial", Leigh explained, meaning sensitised, not truly oily.

"When you stop stripping your natural oils, your skin stops overproducing."

And if you're unsure, it's best to get a proper skin diagnosis.

Tip 9: Jojoba oil is incredible

Kelly swears by jojoba oil as an all-round skin saviour, especially for breakouts and irritated skin.

"It balances it, it is antibacterial because it's not actually an oil… jojoba oil is actually a wax," she explained. "It looks and feels like an oil, but it's not."

Because of that antibacterial action, she says it's one of the first things she reaches for when she or her sister get a pimple.

"If me or my sister have a breakout, that's just the first thing, I'll just be like, cleanse, oil, that's it… and just the most gentle cleanser."

Tip 10: Less is more with injectables.

It's tempting when you come across a Groupon deal or beauty clinic offering an unreal price on injectables. But as someone who used to love a good injectables deal, Kelly wants you to stop and think for a second.

"It's not the thing you wanna get for a bargain, and you can always go back two weeks later and add more once it's kicked in, but you can't reverse it," Kelly warned.

And the golden rule: "When you're choosing a good injector, look at their face."

Tip 11: Never EVER decant your sunscreen.

"Never, ever, ever decant sunscreen into another bottle," Leigh emphasised. "I don't care if it's glass, dark, or made out of diamonds."

Sunscreen is only tested and stable in its original packaging, so changing it compromises its protection.

Tip 12: Glycolic acid fixes a stinky armpit.

If deodorant (the real deal, not natural) isn't doing enough, get yourself a glycolic toner or witch hazel.

Swipe your pits (not after shaving!) and thank Kelly later. "It's the equivalent of exfoliating your face, you'll smell so much fresher."

Tip 13: Clean behind your ears.

"When you're cleansing your face, cleanse behind your ears," Leigh begged.

Yes, all your hairspray, dry shampoo, sunscreen and makeup get trapped there. "Use your fingers or a Q-tip and see how gross it is."

Tip 14: Nappy rash cream is magic.

Dry nose? Flaky patches? Sore skin? Kelly has the fix.

"Use a nappy rash cream under your nose or anywhere that's dry and crusty."

Her favourite is the Weleda Nappy Change Cream, especially under the nostrils in winter.

Tip 15: Your eyebrows are sisters, not twins.

"If you are DIY plucking or maintaining, leave more than you think and don't ever try to even up your brows because you'll pluck away, pluck away on each side until you've got no brows, because your brows are not twins, they're sisters," Leigh said.

If you've paid someone to shape them or had them shaped before, the rule is only pluck if it's a stray.

Tip 16: Don't fear blush.

"We get the question so much about blush placement, and people are thinking, do I, do I not… go ham!" Kelly said.

Tip 17: Respect your skin barrier before using actives.

"If you compromise your barrier by too much exfoliation, too much vitamin C, too much vitamin A, sun exposure, or a lot of different reasons, your barrier is impaired," Leigh explained.

"You'll have breakouts, you'll have dryness, you'll have redness, you'll have sensitisation."

Fix your barriers first (with hydration, ceramides and peptides), then feel free to introduce actives.

Tip 18: Check the back of your legs for rogue hairs.

"I only started doing that in the last year… it's so satisfying."

Enough said.

Tip 19: Most people don't realise what they look like.

Do you think you look "weird" or "bad" in photos? You don't. It's just reality.

"You in the mirror is the reverse of what everyone else sees. You in a selfie is the reverse of what everyone else sees," Leigh said.

"Sometimes that's often why you don't like a photo that other people have taken. It's not that it's a bad photo, it's that's what you actually look like. Your face is flipped to what you're used to seeing. You are used to seeing yourself in reverse."

Revelation, right?

Tip 20: Practice makes perfect.

"Everyone learns from somewhere," Kelly reminded us.

Don't say you "can't" contour, do eyeshadow, or use a GHD or Dyson Airwrap if you haven't sat down and actually tried.

"It's like riding a bike — anyone can learn."

For more tried and tested beauty recommendations, listen to the You Beauty podcast or watch You Beauty on YouTube.

Feature image: Supplied.