In our new column, celebrity dermatologist Dr. Zein Obagi helps us make sense of our skin, tackling all the issues lying between us and complexion perfection. This week, Dr. Obagi helps us get to know the skin we're in a little better so that we can find the right skincare products.

Photo: Jacobsen /Three Lions/Getty Images

When it comes to shopping for clothes, most of us have a fairly good idea of what size we wear, but finding a skincare fit isn't always that simple. With so many options on the market, gone are the days of defining skin as oily or dry, acne prone or normal.

This fall, don't hit the skincare aisle before you get the facts about your face. Read on for my breakdown of skin diagnostics and how to find the products that truly fit your skin.

Thick or Thin
The density of your skin affects how your skin looks as you age. Typically, those with thick skin experience more laxity or skin drooping, while people with thin skin are more prone to premature lines, wrinkles, and dilated capillaries. Although thicker skin is the most resilient, skin that falls somewhere in the middle is ideal.

How to tell: Using your thumb and forefinger, pinch your cheek in the fleshy part. If you have thin skin, the separation between your fingers will be .5 cm – 1 cm. Those with medium skin will feel a 1-1.5 cm separation and thick skinned people will pinch more than 1.5 cm of skin.

What to do: For skin veering on the thin side, look for products with high levels of retinol-the most effective ingredient for skin plumping and strengthening the epidermis. Retinol also aids in improving thick skin because it stimulates the production of collagen and elastin, which makes skin firmer and tighter. A Retinol-rich product such as my Ossential® Radical Night Repair Plus can benefit both skin types

Ossential® Radical Night Repair Plus

Ossential® Radical Night Repair Plus. Courtesy of Zo Skin Health

Oily or Dry
Excess sebum and oil can cause clogged pores, acne, inflammation, and blackheads. Lack of sebum, however, leads to skin dryness and accelerates wrinkle formation-that's why it's essential to keep your skin in proper balance.

How to tell: Wash and dry your face, then blot the skin with a tissue, pressing gently all over the face. If your skin is oily, the tissue will stick and sop up extra sebum. If the tissue doesn't soak up any oil, your skin is dry.

What to do: Those with oily skin should cleanse with a face wash that contains salicylic acid for one full minute and finish with a splash of cool water. Follow with oil-free products and reduce the use of cosmetics as much as possible-even the non-comedogenic ones can promote excess oil.

For dry skin, increase hydration inside and out. Begin by upping your intake of liquids, and high water-content foods. As for topical care, I always caution patients against chronic use of moisturizers, which make your skin more dependent on superficial sources of water. Instead apply products fortified with retinol to stimulate dormant skin cells.

Strong or Weak/Sensitive
Healthy skin is strong skin. If your skin is weak or sensitive, you need to strengthen it.

How to Tell: Sensitive skin is easily irritated by certain products, environmental factors and is frequently inflamed, whereas strong skin is tolerant, even-toned and rarely feels dry or irritated.

What to do: I find skin sensitivity is often caused by long-term daily use of moisturizers. If you have sensitive skin, avoid the use of unnecessary products and chemicals. Protect skin from daily damage with a physical sunblock made with titanium dioxide and zinc oxide instead of a chemical formula. Look for products with anti-inflammatory ingredients such as feverfew, aloe vera and chamomile and avoid the use of products with unnatural additives or fragrances that could further irritate sensitive skin. Once your skin adjusts to the new products you can introduce a retinol or retinoic acid, the most effective ingredient for strengthening weak skin. And remember, always test new products on your forearm to see how your skin reacts before applying to your face.

Oraser Body Emulsion

Oraser Body Emulsion. Courtesy of Zo Skin Health

Thirsty or Hydrated
Your skin age and your real age might be two very different numbers depending on how hydrated your skin is. Alcohol, sun-sessions and sleep deprivation all zap the body of moisture and accelerate skin's aging process (surprise, surprise). Luckily hydrating thirsty skin is practically free.

How to Tell: Pinch the thin skin on your hand, and then release. Your skin should immediately revert to normal. If it takes even a second to recover, your skin is dehydrated.

What to do: Double your water consumption, cut out alcohol, avoid the use of astringent toners and protect your skin from ultra-drying air conditioning or overheated spaces with lotions that offer barrier protection like my Oraser Body Emulsion.

In related news, find out what key ingredients every anti-aging cream should have.

To ask the good doctor a question or topic to tackle in a future column, leave a comment below. Check out his website, ZoSkinHealth.com for more skincare information and get a 15% discount on products when you use the shopping code: AOL3.