Sometimes it seems the authors of self-help books are trying to write themselves out of a job.

A real-estate agent lets us in on how to sell our home without his help. A lawyer suggests we avoid his fees with do it yourself divorces.

Now Janette Rainwater, a Los Angeles psychologist, tells us how we can unravel our mental twists by becoming our own therapists.

"I'm not against people seeing psychotherapists," Rainwater is quick to point out in "You're in Charge: A Guide To Becoming Your Own Therapist" (Guild of Tutors, 221 pages, $8.50 paperback). "That's how I make my living."

But, she says, "I believe that psychotherapy is successful only when the clients also start learning to do self-therapy."

Rainwater, 57, who says her book is being adopted in 20 colleges as a text, has held more than 300 workshops since 1967 in this country and abroad. Her clients have had to learn self-therapy because of her extensive travels:

"They've done some of their best work while I'm gone, a point that has not escaped me."

Rainwater's major emphasis is on "getting control of one's thoughts and learning to direct them where you want them -- the path to self-mastery."

As illustration, she cites a recent overnight ferry trip she took from Athens to Crete. The passengers were warned that rough seas were expected and they might experience seasickness -- and with that pleasant thought to ponder, "I think 98 percent of them did."

But Rainwater -- every time she felt a particularly rough wave might capsize the ship -- pictured herself "rocking in a cradle. It was the best night's sleep I can remember."

Rainwater has taken a variety of therapeutic ideas and techniques -- meditation, gestalt therapy, yoga, psychosynthesis -- and incorporated them with basic nutrition "and whatever works" to come up with a series of mental exercises. Their aim: to get us to see ourselves realistically.

Serious problems, of course, may need the help of a therapist. But we put ourselves through a number of "self-torture" trips, says Rainwater, that can be avoided.

Many people "get angry at themselves" when they think of things they might have done. "If only I had bought gold" . . . "If only I had bought that house five years ago instead of renting. . ."

If you step away, she says, you'll realize "I'm really expecting myself to have 20/20 vision" into the future, which is impossible.

Another "way to make yourself miserable" is by "doing a sentimental memory trip -- by thinking how much better the past was."

Ask yourself, she advises, the "two magic questions:"

"What am I thinking right now?"

"do I want to continue?"

Then divert yourself, she says, from detrimental thoughts to "what I'm going to make for supper" or "how the kids are doing so well."

Two tools rainwater uses with clients and incorporates into her book keeping a journal of thoughs and activities and writing an autobiography. Both help the writers become more aware of themselves, she says.

Many people, she has discovered, begin their personal histories unable to explain "why they got married, or why they're in the job they are or why they're living in this town."

One client, a woman with three children whose husband left her, used her journal to argue out her anger. Now she's using it to lose weight, recording everything she eats.

"Many people come into therapy with the complaint, 'I'm not happy,'" she writes, and "ask for a recipe to achieve happiness." Rainwater believes "the pursuit of happiness is futile. . .

"Happiness is something tht you realize you are experiencing NOW . . . whether it's when gardening, nursing a baby, watching a sunset, talking with a friend. . ."