The cardinal rule of skin care, is (of course), “Don’t forget to wear sunscreen.” This edict is repeated a zillion times a day by dermatologists around the world, all of whom would likely list SPF as the one product they’d want with them if they were stranded on a desert island. But for Jennifer Holman, MD, a Texas-based board-certified dermatologist who was diagnosed with melanoma in her early 20s, this commitment to sun protection is even more personal.

Back before she was educating her patients on the benefits of sunscreen, Dr. Holman was spending quite a bit of time at the tanning salon—something we all now know is terrible for your skin. “As I got to college, I got not just one tanning bed membership, but two [memberships] so I could go twice a day,” she explains. “I tanned regularly in a tanning bed for about five years. I definitely neglected SPF and if I did use it, it was the SPF 4 tanning oils.”

While five years may seem like too short of time to do such extensive damage, studies have shown that one tanning session alone can increase the chances of developing melanoma by 75% before the age of 35. So after spending half of a decade partaking in the dangerous practice, Dr. Holman received some scary news.

“It was during my fourth year of medical school—within a week of finding out I had been matched into a dermatology residency program—that I happened to ask one of my future partners about a mole that my husband noticed had changed,” she explains. “I didn’t think much about it before because the change was so gradual.”

Luckily, once the doctor biopsied the lesion and determined it was in the very earliest stage of melanoma, the mole was relatively easy to surgically remove and no further treatment was required. “I was anxious as I had never had surgery like that before, but it was a simple and almost painless procedure,” says Dr. Holman.

Unfortunately, Dr. Holman’s experience isn’t a rarity: Over the last 30 years, more people have been diagnosed with skin cancer than all other cancers combined. In an effort to help prevent others from suffering through an experience similar to her own, Dr. Holman is sharing all of the sun safety tips she wished she’d always known.

1. “Base tans” are a myth

If you’ve ever wondered if you should get a “base tan” before vacation to avoid burning on the beach, the answer is a resounding “no.” “Any tan is your body’s response to DNA damage by UV radiation,” warns Dr. Holman. “The way I explain it to patients is that a base tan is like smoking five cigarettes a day to get ready for a vacation when you’ll smoke twenty cigarettes a day.” Ultimately, there is no such thing as achieving a “healthy” tan when it comes from UV radiation.

2. Melanoma doesn’t always appear as a new mole.

Many people think that melanoma shows up in the form of a new mole that appears out of nowhere, but that’s not always the case. “Melanoma can both come from an existing mole or present on its own,” says Dr. Holman. “Watching both for changing lesions and new growth is very important.”

3. Annual skin checks should be a non-negotiable

Say it with me: Skin checks save lives. Even the most diligent SPF wearers need to be getting annual skin checks, and if you have over 50 moles or a history of tanning bed use, Dr. Holman says it’s even more important that you receive an annual skin exam. Do yourself a favor and book an end-of-summer session now.

4. The sun causes more issues than just skin cancer

Skin cancer aside, the sun is often the catalyst behind a variety of skin concerns, like wrinkles, hyperpigmentation, and sagging skin. “My teenage daughters are more scared by my wrinkles than they are by my surgical scar,” says Dr. Holman. “Remember that exposure to UV radiation not only increases your risk for melanoma and other skin cancers, but it ages your skin prematurely as well.”

5. Reapplying SPF is non-negotiable

“The biggest mistake that I see patients make with regards to protecting themselves from UV radiation is not reapplying their sunscreen,” warns Dr. Holman. “Remember, even with a high SPF, you need to reapply every 90 to 120 minutes when in the sun, and especially if you are in the water [at a pool or beach].”

For those that wear makeup and are worried that reapplying SPF will smudge their foundation, try spritzing a product like the Kate Somerville UncompliKated SPF Soft Focus Makeup Setting Spray SPF 50 every few hours for added protection.

6. Don’t skip out on self-exams

To help prevent a delayed diagnosis—which can have devastating consequences— it’s important to examine your body for mole changes as often as possible. This includes checking your front, back, right, and left sides, with arms both down and then raised. “Also, examine the back of your neck and scalp with a hand mirror,” advises Dr. Holman. “Part hair for a closer look at your scalp, bend your elbows and look carefully at your forearms, the backs of your upper arms, and palms.” Finally, don’t forget to look at the backs of your legs and feet, as well as the spaces between your toes and your soles.

7. Know your melanoma ABCs

When it comes to melanoma, remembering your alphabet is the key to recognizing any potential skin cancer. Regularly evaluate moles for the following, and if you notice any of these symptoms, see your dermatologist.

A is for asymmetry

If you draw an imaginary line through the center of a mole, do both sides look the same? If not, the mole is asymmetrical, and asymmetrical moles have a higher likelihood of being cancerous.

B is for border

Non-cancerous moles have smooth borders, whereas malignant growths have uneven ones. So, keep an eye out for moles that have scalloped edges, notches along the border, and other irregularities.

C is for color

Typically, moles are a single color throughout (you can can brown, tan, or even red moles on skin) so moles with multiple multiple colors raise a red flag, including brown and black spots.

D is for diameter

Benign moles tend to be rather small. So, any mole that is larger in diameter than a pencil eraser should be checked out for potential cancer.

E is for evolving

Most benign moles look the same year after year. “An evolving appearance could indicate the presence of cancer,” says Dr. Holman. “Be alert to moles that change in shape, color, or size or that bleed or itch so you can report them to your dermatologist.”