First, a riddle: What's harder to find than a No. 1 spouse, perks up the self-esteem better than a good shrink, and costs more per hour than a Maserati mechanic? Answer: the perfect tennis pro.

But finding the perfect pro can be as problematic as adopting a guru. How do you know when you've found the perfect Master? You just know. The right pro gives the player a sense of well-being, of growth. You get exactly what you need. A bit more (but certainly no less) of a challenge than your game can handle.

The perfect pro may dispense a fresh start for the neophyte - new grip, new strokes, some Astaire-by-the-numbers rootworks footwork. But for the seasonally rusty, it's usually more subtle: "Bend the elbow here, a bit more follow-through there . . . practice, practice." And for the tournament player, well, a private lesson usually means some strategy on the run and a good sweat.

How does one come to know such truths? How does one become expert at choosing the true teacher over the false prophet? One must wander - and experience - the crowded tennis wilderness alone.

Let's say you're hitting the ball deep and solid with an Eastern grip. The perfect pro would never insist you try the Continental. That's a sure sign of counterfiet advice, and, at $20 to $35 an hour, it's also a signal to cut and run. On the court and off, you've got to hknown when to cash in the chips.

Just last week, I was dispatched on assignment to whack, slap and stumble about courts across the fair city in search of the perfect tennis pro. It was a sometimes buffoonish ballet, and I paid dearly for the privilage - in blisters, piasters and pulled muscles. I didn't find the perfect pro, but I hit hitcher and yon, interviewed teacher and teachee and filled this report:

Over the phone, they talk a mean game; some even promise pie-in-the-sky. But don't let the big-name pro jive you. The best player doesn't always make the best teacher. (No names, here: You know who I'm talking about) On the other hand, the top players seem to gravitate toward the big names, whose repute, ill and otherwise, travels fast by word of mouth. Which means a Just Anybody (player) may not able to line up a Somebody (pro), though word sometimes trickles down and the Somebodies get spread around.

So, if you're looking for a pro, you'd do best to start by asking other players how they like theirs. You know how you play; you know how they play. Go watch their proprescribe for another's ailing serve and guage firsthand whether you'd do well to sign up at for a lessons that may cost 50 cents a minutes.

At the lesson's outset, the pro should ask what you'd like to work on. If you want to hit forehands for a half an hour, say so. Or you may prefer a general shakedown. With the tennis explosion, all manner of "pros" are lurking about. As in any therapy, have a little faith - but don't hesitate to throw one over for another. Remember, you're the ones who's paying to play.

Since many area come with the court, you've got rent one to rent the other. Some may discreetly agree to dispense a lesson on a public court in their spare time, which means you pay about half-price. Another path to bargain enlightenment: Scout the local college tennis team. The coach might tune you up after practice for a modest fee ($5 to $10 an hour), or his top seeds may be itching to a launch their professorial future witha bit of free-lanching.

But a friend who hits a better game is cheaper than all the rest. Pals like that are pals indeed if they will meet you on the court. No need for the private lesson - until the plateau, when you may require professional surgery on the strokes. If you start beating your friend, find another.

As with pros, good partners are hard to find, and far more dependable than backboards. Their loss can be more devastating than divorce. Among the darkest depressions one local tennis-playing lawyer ever experienced was losing two steady weekend net partners in a corporate relocation. "One moved to Texasand the other moved to Norway," he said, "It broke my heart."

And, without constant practice, lessons are a waste.

Tennis clinics also offer low-cost hope for wobbly forehands, a chance to meet others who play at your level of the game, and pro supervision. At the Arlington Y Tennis Club, I was invited to join the sweating camaraderie of seven women on the mean end of a booming ball machine.

Ka-chunk, ka-chunk. A cross-court forehand, a cross-court backhand. Grin. Wink. Grimace. Ka-chunk, Ka-chunk. Courtside romance has been known to bloom between ka-chunk, smiled to pro, and evidence of enmity has been known to fester at the net.

"Your opponent may try to lob over your head, but 18 out 10 lobs will be bad and you can put it away," he said. "If you have a husband, wife or boyfriend you want to get rid of, the net's as good a place as any." A few smirks suggested that this might be the cae.

Quickly, the dark fanstasies dissolved, and the pro aimed a videotape camera to capture my dazzling footwork. Heh, heh, uh, so maybe the backfoot was coming around on the forehand, and maybe the backswing was a bit too high. It been a long winter. ka-chunk, ka-chunk. Ah, Perfect Shot, scintillating form . . . Oops, there goes the foot again, and the ball into the net Blush.

Instant replays can be humiliating, but they burn an image of what's right (and wrong) into the synapses as indelibly as Gino's jingle. You must walk away feeling like a Keystone KOp, but at least you walk away with something.

A briefly narrated videotape can be worth a thousand words from a video-less pro. Still, it's just a tool, and tools alone can't save an ailing game. As good Pro - and lots of practice - may. I encountered a number of pro-types lurking about, and compiled some categories to consider:

The Chattterbox. This pro-type talks too much. He talks so much , in fact, the advice tumbles out like a broken record. The Chatterbox, also known as The Yammerer, confronts the pupil with such a torrent of instruction, the words whizz past the ear with the ball. He wants to demonstrate how much he knows about the game; every shot is served up with generous monologue. Some players need a litany of reminders, but others will find they cannot concentrate around The Chatterbox, first cousin to The Jerk.

The Jerk. It's easy understand why The Jerk is related to The Chatterbox: The Jerk likes to talk, too but he prefers lecturing at the net. Between shots, Every shot. Oh, The Jerk may let you hit a couple of shots, only to summon you forth, just when the brow is beginining to feel nicely moist and the forehand is starting to click. Yawn. Hit. Lecture. Yawn. The Jerk can't take a hint. Hit three. Lecture. Hit two. Lecture. Three backhands. Three forehands. Lecture. Lob. Lecture. serve. Lecture. Volley. Lecture. The Jerk will save the tennis togs a wash. No work means no sweat.

The Human Backboard. Good old H.B. For $25 an hour, H.B. will let you shot bounces off his racquet, whence it will drop at your feet, just so. H.B. never says a word, or whispers so softly you cannot hear. Is H.B. actually a robot? A family of H.B.s, rumor has it, was once cloned from a ball machine, which are also accurate on the return and provide similar compainionship.

The player Pro. The P.P. prefers to teach through repetition - hitting, say, a dozen shots to the forehand, the backhand, letting the player feel his way through the shot. "If they don't learn anything, at least they go to the showers with a good workout,"says one P.P., who sprinkles tidbits of advice throughout the lesson. The P.P. recognizes that tennis styles are as diverse as the people who play. P.P.s never try to change a game that works. Not so with The Proselytizer.

The Proselytizer. This pro believes his way is the only way. He'll strip away securities - old habits, good and bad. Sorry, chaps, if the Eastern grip works, you'll just have to move the thumb over. Of course, you'll feel naked and uneasy, hit bad shotsand feel compelled to fork out for more lessons to transform a game that worked. Avoid The Proselytizer unless you need a complete overhaul.

The Pleasure Pro. You're okay, he/she's okey-dokey. The object here is to have fun. This pro breaks tennis down to the basics, as in keep-it-simple, and works on improving a couple of strokes that will shore up sagging confidence. No hardcore reformistshere, usually older pros who never made it on the circuit - which doesn't mean anything, really, except that they often come home to roost at one of the better clubs. What makes the Pleasure Pro a good pro for the medium playermakes him not so good for the the Wimbledon-bound: No competitive edge. He may not grant profound insight, but you'll come off the court feeling that there's life beyondthe volley.