'Nothing looks better in your 50s than sunscreen in your 20s': Here are your must-know sun tips for summer

Jennifer Garner said it best about sun protection in the life advice she gave to Denison University graduates at their commencement ceremony two years ago.

"I'm going to say this because everyone says it, but you won't listen because nobody does: Nothing looks better in your 50s than sunscreen in your 20s," said Garner.

The "13 Going on 30" star's advice to graduates is what dermatologists preach year-round, but especially in the summer. Protecting your skin from the sun is crucial, both for healthy-looking skin and for helping to prevent skin cancer.

"Good Morning America" tapped Dr. Whitney Bowe, a New York City dermatologist and author of "The Beauty of Dirty Skin," to share the top things every women needs to know about sun protection.

Here are Bowe's nine tips, in her own words.

1. Sunscreen alone isn't enough

Sunscreen is one important tool, but we also have a number of synergistic, proven ways to optimize and boost our sun protection from the inside out and the outside in, taking it to the next level.

A diet rich in antioxidants appears to help prevent DNA damage and cancerous growths that can result from UV radiation, according to a study published in the Journal of Skin Cancer.

And recent studies show that taking an oral supplement called nicotinamide, a form of vitamin B3, every day can actually reduce the risk of developing skin cancer.

2. Periods can increase the risk of sun damage

Women may become more sensitive to the sun around the time of menstruation, increasing the risk of sun damage, including painful burns.

3. Put the oxygen mask, or sunscreen, on yourself first

When I am at the beach with my family, I watch mothers slather sunscreen all over their children while neglecting their own skin.

Whether it's because we don't think we have time to dedicate to our own care -- or, if we think we are getting "a base tan," "a little color," or "some vitamin D," none of these reasons is going to prevent a skin cancer diagnosis.

We have so many options when it comes to sun protection. Making time to use them and to protect your skin is always worth it.

4. Remember the shot glass rule for reapplying

My rule of thumb is to apply a shot glass full of sunscreen every two hours or, more frequently if you are swimming or sweating excessively.

That is quite a lot of sunscreen, which is why I love UPF (ultraviolet protection factor) fabrics for myself and my family. You don't have to apply sunscreen anywhere the fabric covers, which means that if I wear a sun protective lightweight top called a rash guard, I do not have to apply sunscreen to my back, chest and arms.

So, my approach is truly a combination approach -- I apply my sunscreen every two hours, but I cut down on how much I need to use because I wear UPF swimsuits.

5. Your hat needs to include protection too

If you can see sunlight through the weave of your hat, the hat is not protecting your skin adequately.

You need a tight weave hat with a wide brim to truly protect your skin. It's such a simple step, but it makes a huge difference.

I recommend looking for hats with the word "UPF 50+" on the label.

6. Sunscreen benefits still outweigh the risks

Two of the ingredients many people are especially concerned about in sunscreen are oxybenzone and octinoxate.

Physical blockers (mineral blockers), like zinc oxide and titanium dioxide, have minimal skin absorption, but many chemical sunscreen ingredients have been found in systemic circulation and tissues in humans.

Third party testers, such as Consumer Reports, consistently find that many chemical sunscreens perform better than sunscreens that contain only physical, or mineral, blockers. So, many of my patients are currently weighing efficacy against safety questions in selecting their sunscreens this summer.

Overall, the FDA is still saying that the benefits of sunscreen outweigh the risks and I absolutely agree.

7. Choose different SPFs for different activities

On a daily basis, if I'm layering on makeup and heading to the office, an SPF 15 or 30 is sufficient.

However, if I'm heading to the beach or spending significant time outdoors, I typically use SPF of 50 or above for myself and my daughter.

Higher SPFs can be more forgiving. Meaning, in real life, in real time, most people don't actually apply sunscreen exactly the way the instructions explain that you should -- they don't use enough of it, and they don't reapply it as frequently as they should throughout the day.

So, in the real world (not in a lab setting), your SPF 30 might end up protecting more like SPF 15 based on how you use it. If you reach for a tube that says SPF 50 or 60, you're giving yourself a bit of a buffer.

8. Know that skin color does not matter

Anyone can develop skin cancer, even if you have dark skin.

In darker skin, it is frequently not detected until very late stages when it is more likely to be fatal.

So, no matter what shade your skin is, you still need to use sunscreen, wear a sun hat, stay out of the sun during peak hours, and consider UPF clothing and proven supplements.

9. Remember ABCDE

You can develop skin cancer on areas of your body that are not frequently in the sun and even under your nails or on your lip.

Non-melanoma skin cancers can look like pearly red bumps, red scaly patches or even scars that appeared without any history of trauma in the area.

When it comes to melanoma, the most deadly form of skin cancer, I remind my patients to remember the "ABCDEs of Melanoma," which includes evaluating the characteristics of a mole:

Asymmetry.
Border irregularity.
Color of the area.
Diameter of the mole.
Evolving size of the area in question.

I recommend that my patients have an annual skin check and watch for what I call an "ugly duckling." which means a mole or freckle that stands out to you, seems to be changing, itches, bleeds, or essentially seems to differ from the other freckles/moles on your skin.

When it comes to non-melanoma skin cancer, if something new appears on the skin and doesn't resolve, or if you have a spot that bleeds or scabs, it's worth getting it checked out.

Editor's note: This story was originally published May 27, 2019.