Q. I want my eight-year-old to start taking tennis lessons but I'm afraid she may be too young. What's the right age to begin? A. There really is no "right age." Whether or not your daughter is ready to take up the game depends on several factors -- her physical coordination, attention span and, most important, her enthusiasm for the sport. Although Tracy Austin began toting a racket at age three, starting so young can just as easily result in a big fizzle. Most pros consider eight or nine a good age to begin. Q. I'm ashamed to admit that my son has taken to throwing his racket and behaving like a crybaby when he loses. What should I do before he turns into another Ilie Nastase? A. Next time he acts up, slap him with a one-week playing suspension (assuming the tournament officials don't beat you to it), and then make him buy all future rackets with his own pocket money. Easy, huh? Q. I'm a pretty good 13-year-old player who would like be in some tournaments this summer. Where do I get information? A. This year you're in luck: Tennis Life magazine has formed a new junior circuit, complete with computer rankings and playoffs just like the big time. The Prince Mid-Atlantic Circuit features over 20 tournaments for "middle range" junior players (boys and girls 12 and under, through 18 and under) running through early September. Join the circuit for a mere $2 plus individual tourney fees. (For details call 593-5276.) Q. I've been pitching balls to my 10-year-old for the past two summers. Is this O.K., or will he end up with my lousy strokes? A. Probably no harm done, but as soon as it looks like he can give you a run for the money, hand him over to a qualified pro. Q. My daughter seems interested in tennis, so should she begin with private or group lessons? A. Ideally with both, but the usual private lessons cost five times as much as group instruction. In a small group your daughter will learn the basics and make new friends with whom she can practice after class. You can always sign her up for private lessons as her game progresses. Q. What kind of equipment will my son need to play this summer? Does it have cost a lot? A. Probably not as much as you think (and considerably less than for golf.) Assuming he already has shorts and a T-shirt, all he'll need is a racket, tennis shoes and a hat to ward off the sun. The racket should be light enough so he can swing level without having to grip it around the throat. lFor 5- to 10-year-olds, substandard size rackets are available for $10. A good pair of tennis shoes (no running shoes, please) will cost about $15. Tennis balls are usually provided by the program, but a nutritious breakfast and a pat of encouragement is up to you. Q. We can't decide whether our kids should go to an all-day tennis camp or just take two-hour sessions. I'm afraid our eight-year-old daughter will wilt in the sun. Any ideas? A. Learning to play should be a fun experience, not an endurance contest.If you have a question about your daughter's stamina, by all means enroll her in a shorter program. The advantage to all-day camps is that the kids can work on fundamentals in the mornings and practice their newly acquired skills in afternoon competitive sessions. Q. How do I know if a particular camp is right for my son? A. Look for quality tennis instruction and a small student-teacher ratio. Where you pay less you might also find a horde of kids and one very beleaguered instructor. Select a program with experienced personnel -- they don't have to be world champs, just enthusiastic "tennis people" with a fondness for munchkins. Q. My daughter is improving so fast, I dread the day she beats me. What do I do then -- take up golf? A. Why not just grin and bear it? And start working extra hard on your game.