The first thing you should know is that there are 109 known ailments that fall under the broad category of arthritis.

The second thing is that copper bracelets won't help. Nor bee stings. Cod liver (or any other) oil won't lubricate your joints. Massive vitamin doses of E, A, D or C need a heap of proving. Special arthritis diets, for the most part, are useless, if not actually counterproductive. And even the Chinese do not use acupuncture to treat arthritis.

It is even arguable whether that poor old grandmother in the TV ads who just has to get up and make breakfast for her family - no matter how much she hurts - should be masking the pain with the medicine she's selling. Maybe she should be letting her family serve her breakfast in bed.

Of course aspirin in massive doses is a major tool in treating some forms of arthritis (as are other anti-inflammatory drugs) and is also useful in small doses for milder forms. But is ought to be with a doctor's knowledge and approval.

If you are one of the 75 million Americans who have symptons affecting joints or muscles, there is a vast body of medical help available and a lot you can do for yourself at home.

First, of course, you and your physician must determine which of the 109 varieties is causing your particular ache or if, indeed, it is caused by something else.

And then, it becomes a matter of how best to cope.

According to Dr. James F. Fries, director of the Stanford Arthritis Clinic, about 22 million aching Americans have "moderate" problems from arthritis and perhaps 3 million are affected severely.

Most people who have arthritis have the kind that falls under the category of cartilage degeneration, osteoarthritis or osteoarthrosis. It's sometimes known as the "getting-old" diease or the "wear-and-tear" diease because, sooner or later, anybody who lives long enough is going to experience it to a greater or lesser degree, if not in the hip or the knee, then in the feet or the fingers. Some people sooner rather than later.

Arthritis, says Dr. Fries, has become "an allegory for the aging process," and in the past "the temptation was simply to tell a patient, 'Well, you can't do much at your age,' or, 'You'll have to give up this activity or that.'"

But today, Fries says, "The emerging psychological and sociologist literature suggests that frustration, decreased self-image, alienation, loss of social contact, loss of other physical activity, all accelerate the process we know as aging, and create depression, the feeling that life's not worth living anymore, that all of the good times are behind you . . . so if we contrict someone's activity because of arthritis, what we do is cast a stone that causes very, very wide ripples."

Moreover, Fries says, the old conventional wisdom that joints just wore out with age is being supplanted by new knowledge that the body suffers much more from disuse than use, that the more a body and its parts are used, the longer they last. This has been pretty much established in terms of cardiac and muscle fitness, but "with the joints this has been a hard concept to accept."

Nevertheless, "the joints are supported by a variety of structures-ligaments, underlying bone, tendons, muscles which are strengthened by exercise."

Of course that does not mean any exercise for any kind of arthritis, Fries says, although most doctors now feel that all forms of arthritis benefits from some forms of exercise. (Exercise will, at least temporarily, exacerbate inflammation in rheumatoid arthritis, and some physicians prescribe enforced rest, at least in the beginning stages of treatment.)

But for the most part, exercise is beneficial, even essential. Cartilage, for example, is completely nourished by and eliminates its wastes by motion alone.

Of course, no one expects any arthritis victim to start right out in the Boston Marathon (in which Dr. Fries, incidently, finished about 5,050th out of 11,000 this year). Mostly because it's too jerky motions," said Fries. "Tennis, for example, is really not best for someone with arthritis. What you do want is to build suppleness of the joints . . . aiming for muscle tone . What you really want is swimmers' muscles, so swimming turns out to be an excellent exercise."

So. says Fries, are bicycling easily or walking. He adds this caution: Listen to body signals. Pain is a message. If there is a lot of pain either during exercise or right after, or if pain kicks up the next day, you're probably overdoing.

"Drop down a level," he suggests, to isometrics, perhaps, or even to just stretching several times a day. One arthritis patient whose problem was in her hands found playing the piano helped significantly. Once you drop back, you can soon start building up exercise again to a more energetic level. If you can get to the point where you "break a sweat," you've probably reached the aerobic stage so beneficial for the heart. Overweight can make many forms of arthritis worse, so a proper nutritional, low-calorie diet, coupled with exercise, is recommended. The old home remedy of vinegar and honey is both icky tasting and fattening. And useless.

Dr. Fries' concern with "logic in medicine" led to the publication a few years ago of book called "Take Care of Yourself," notable for its system of easy-to-follow flow-charts offering guidance to the lay reader as to when to seek medical assistance or provide home treatment in a variety of situations.

The book and the communications system were well received and Dr. Fries has now adapted the technique to a just-published book on his own specialty, "Arthritis: A Comprehensive Guide," published by Addison-Wesley.

Designed to further the concept - which is gaining wide acceptance among doctors - of the importance of people talking increased responsibility for their own health, the book leads the layman, step by step, with the aid of the flow charts, through the various symptons of eight broad categories identified by Dr. Fries, into which the known types of arthritis generally fall.

In addition to cartilage degeneration, there are:

Synovitis (which includes rheumatoid arthritis and lupus), attachment arthritis (the inflamed ligament attachment to bone), crystal arthritis (gout, for example), muscle inflammation, joint infectious (bacteria, usually staphylococcus or gonocuccus in the fluid of the joint), local conditions (tennis elbow, frozen shoulder, low-back strain) or general conditions (aching and stiffness throughout the body, not altogether pinpointed as to specific cause, but responsive to treatment).

The charts also help the patient decide when a doctor should be called or when home treatment should be administered.

Of course all arthritic conditions should be diagnosed by a physician, but the Fries guide will help the patient understand his or her particular problems so that instructions for treatment and medication, when called for, can be followed with intelligence and awareness. Or it can help the mild arthritic implement home treatment with confidence and hope.

Dr. Fries is devoted to the premise that arthritis should never be an excuse for dropping out of life or giving up life's pleasures and he deals candidly and sympathetically with problems ranging from opening jars to bathing, to using the toilet, to having sex, to holding down a job.

"It is," he sighs, "often the little things - trying to get your socks on in the morning, for examle - that are so hard. More people lose their self-image about some little thing that stymies them. It's like a 20-foot wall. Sometimes it just takes a little trick. . ."