If you’re on the gray side of 40 in our look-at-me culture, you’ve stared into a mirror and seen yourself slipping into decrepitude like fingers on an icy ledge. You decide maybe some “work” needs to be done.

However, if you’re thinking of plastic surgery to make you look younger, don’t do it. I repeat, do not do it. I have that from an expert, but more on that later.

When we go to gossip websites to get our celebrity fix, we stare critically at photos of stars and wonder how much plastic surgery was required for them to always look terrific. (But, of course, we never see how they look at 7 a.m.)

Then, we go to other websites and check out the “face-lifts from hell” and think, “Oh, oh.”

Thus begins our curiosity about the surgery that has us holding our breath and reaching for a mirror when the bandages come off.

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Tim Miller, M.D., is a top cosmetic and reconstructive surgeon in Los Angeles and a professor emeritus at UCLA Medical Center. That means he has worked on some of those beautiful people on tmz.com and in People magazine. His peer reputation rests on his reconstructive work with burned and disfigured patients, but the two things are first cousins. They both involve reshaping flesh.

Miller is an approachable, energetic man of 74 who grew up in La Mesa and holds the Bronze Star for doctoring villagers while getting shot at in Vietnam. Before he tackled our topic, he lightly groused about having strained a muscle lifting weights at his Mulholland Drive home high above the lights of L.A.

You and I are not movie stars, but we need advice as much as Warren Beatty (not that he’s had work done, wink, wink).

I first asked Miller to react to a plastic surgery advertisement I saw that promised to make patients look 15 years younger.

“I don’t like that. I personally don’t think it’s appropriate.”

Looking younger is not the proper purpose for cosmetic surgery, he says. “The goal should be to look better. People know you’re, say, 50, so an attempt to look 30 fools no one. Everyone has seen someone who’s had plastic surgery, and their face doesn’t look consistent with the rest of their body.

“If people ask, ‘How many years will this take away?’ I tell them, ‘It’s not going to take any years away. It’s going to make you look better.’ ”

What is the worst motive for having plastic surgery?

“There are several: Having unrealistic expectations, doing it for someone else, to attract or keep a mate, or to get a job. That takes the surgery away from the person. You do it to look your best. That’s a healthy sense of vanity. If you see extra skin on your face and you would like it removed or tightened to enhance your looks, there’s nothing wrong with that. You want to look like yourself, but look better.”

Let me ask about what you call a breast augmentation, but all the rest of us call a boob job. Does the motivation for that come from the patient or from a man in her life?

“It should definitely come from the woman herself, not from a man. I’m sure there are many who have done it to make their husband happy, and I have nothing critical to say about that. But in general, you want to do surgery for yourself, not someone else.”

(Miller said, “No, I haven’t,” when I asked the obvious question: “Have you yourself had a face-lift?” However, he should have felt flattered that I had to ask.)

What’s the most common cosmetic surgery?

“Liposuction, I suppose.”

Is that a tummy tuck?

“No. Liposuction is sucking out unwanted fat. A tummy tuck is when, let’s say, a 40-year-old woman has had two pregnancies. She’s got extra skin in her abdomen. An abdominoplasty removes that extra skin and restores a nice-looking contour to the abdomen.”

Does it leave a scar?

“Yes, but one that can be hidden by a bikini. Almost any surgery will leave a scar. That’s one of the things the plastic surgeon must explain to the patient. The same with complications. In any surgery, there can be complications.”

Miller says beauty standards change and can be faddish. Lip augmentation is an example. It’s normal for the lips to thin as they age; you can see it as people reach the late 30s. Miller also says the injectable to fatten lips is quite safe.

Reminded that some people with lip jobs look like blowfish, he says, “I’ve seen that, too. I don’t find it attractive.”

Let’s say someone comes to you and wants a breast augmentation, or whatever, and you say to yourself that this woman looks fine as she is.

“Then, I tell them so, absolutely. When I see a young woman who is relatively naive and has a very decent figure to start with, I make sure she’s aware there’s going to be a scar, and it may be visible. There may be a complication. Any implant in the body can react by getting hard. If my heart is not in the operation, I won’t do it.

“With any procedure, if I don’t feel it will make the patient look better and therefore happier, then I won’t do the surgery.”

Regardless of their wishes?

“Regardless of their wishes.”

He says cosmetic surgery itself doesn’t take as much time as putting the body back together, “so it looks like I wasn’t there. I like to think of it as doing something that’s not obvious, but certainly can be seen if you look at before-and-after pictures.”

Miller describes the surgery to enhance a weak chin as “not very difficult,” but that a “nose job” is a very complicated operation. Additionally, unlike almost all other procedures, any alteration of the nose has the potential of changing a person’s basic appearance.

He tells the story of a patient who had his nose substantially reduced, then returned several years later to have it built back up. His reason was that he no longer looked as though he fit in his family.

One operation Miller will do on a man and not a woman is to remove the “turkey wattles” on the neck.

“It’s very hard to cover that scar. Men in that particular area heal much better than women. I’ve seen that operation in women, and you can really tell that they’ve had it. In a man, it becomes almost imperceptible after six months.”

The turkey wattles on a woman can be removed as part of a face-lift.

One development of aging that makes women self-conscious is the loose flesh that accumulates on the back of the upper arm. Miller says removing that is another operation he won’t do because it leaves unsightly scarring.

Here’s a hypothetical: If a typical patient could afford only one procedure, what’s the one that would make the biggest difference for the least money?

“I never suggest an operation, but a procedure that is consistently gratifying to patients, and can be done as an outpatient, is the upper and lower eyelids. It doesn’t look like they’ve had surgery. When they’re healed, they look better. People who have just had their eyes done will tell you not very many people notice at all. That would be what I would pick.”

Miller says the best precaution in seeking a competent plastic surgeon is to make certain they are certified by the American Board of Plastic Surgery.

“Does that guarantee the best surgeon in the world? No. What it does do, it assures that the doctor has been in a residency in which they’ve had increasing responsibility, and have demonstrated skill to the satisfaction of the examiners.”

He says although other surgeons might correctly claim to be “board certified,” you need to ask, “Certified in what?” Being certified in, say, general surgery or ophthalmology does not a plastic surgeon make.

Miller says it is a mistake to equate high fees with talent. Before selecting a surgeon, a prospective patient should call the state medical board to check on possible complaints.

“Finding the right surgeon can be very difficult. It’s a risk. It’s hard to determine skill levels. I know of well-trained surgeons who get average results and are not really that good.”

What would a typical Hollywood star ask of you?

“The same thing a regular person would ask. It’s no different. By and large, the bigger the star, the easier they are to deal with. They have very specific requests. They are successful in their business. They know what they want. There’s no nonsense. I’ve had several use false names, but usually they don’t really care (that it’s known).”

What is the risk of infection?

“Rare, especially if you’re operating on the face. The blood supply there is much better than anywhere else. If you get an infection, it’s unusual, very unusual.”

Does it bother you if people go deeply into debt to get plastic surgery?

“If I knew that someone was going heavily into debt, I would try to talk them out of it, because that could carry over into their perception of what was done.

“Cosmetic surgery is expensive, very expensive. A typical face-lift will cost between $12,000 and $20,000.”

I’ve always said there are two things that won’t save a marriage — having a baby and buying a new house. It sounds like there’s a third.

Miller smiles. “Cosmetic surgery.”

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Though you might think you’ll never live long enough to be as old as you now look, before you jump onto that operating-room gurney, remember: No matter the skill of the surgeon, he or she can only affect how the world sees you, not the way you really are.