The fight is on against racism, sexism and agism. But there's a little-discussed "ism" that can make life miserable, awkward or just plain uncomfortable for the southpaw minority.

"Rightism" pops up nearly everyhwere, since the right-handed majority seems to have arranged nearly everything for their convenience, from telephones to water fountains.

Sometimes the discrimination is subtle. Take, for example, pinball machines, gum wrappers, playing cards and Metro farecard grabbers. More obvious: scissors, can openers, and writing arms on school chairs.

And consider the language: No one wants to be left out -- most prefer being right on. You can do without a left -handed compliment or two left feet, but a right -hand man is indispensable.

One reason why proportionally more let-handed than right-handed people smoke cigarettes, say University of Michigan researchers, may be the stress caused by living in a world not designed for the estimated 12 percent of its population who favor the left hand.

"They go through life feeling klutzy or uncoordinated," says militant lefty Peter Neiman, "never connecting the fact that it comes from often using improperly designed tools."

Neiman is doing his best to change all that. His mail-order company Aristera (classical Greek for left, which means superior, fine, the best -- "a shinning exception to language's Great Lefty Put-Down") specializes in tools and products designed with left in mind.

Neiman, a management consultant with degrees in science, philosophy and logic, got the idea 13 years ago when his left-handed, recently-widowed mother asked him to find her a left-handed can opener.

"It took me six months to find one. I was furious.

"It dawned on me that I ought to try my hand (left, of course) at starting my own business. The market was obviously there."

But despite his gathering or designing everything from a lefty wristwatch to a southpaw's spiral notebook, Neiman discovered "the world wasn't beating a path to our door.

"The average lefty feels adjusted -- they can make do. But the key to penetrating the market is to educate lefties that they shouldn't modify their body to suit the convenience of designers of a tool. They should get a tool that suits them and keeps them from expending extra energy fighting something they shouldn't have to fight.

"For example, a left-handed pen may change a left-handed child's whole outlook on school and writing. It has a fine tip and quick-drying ink so they don't wind up smudging their work and their hands and getting graded down for being sloppy."

Being left- or right-handed also affects "how you think and handle life," Neiman writes in "The Lefty's Survival Manual" (Bantam, $2.95).

"The human-brain is really two half-brains, sometimes refered to as the left and right hemispheres. The two khemispheres have very different ways of solving problems and most people 'prefer' one side to the other.

"The dominant hemisphere (left for righties) likes to look at things logically, taking one step at a time. The other hemisphere likes to solve problems holistically, looking at all the factors at the same time and coming up with an intuitive answer."

This may explain why lefties are "more likely to come up with uniquely different solutions to problems," says Eniman. "Studying left-handedness is a tunnel into a whole new perspective on human behavior."

One quality lefties lack, he notes, is modesty. "Make a list of all the famous people who ever lived, and then run a pencil through the occasional right hander who snuck in."

Ramses, Alexander the Great, Julius Caesar, Leonardo da Vinci, Michelangelo and Napoleon are early members of the Lefty Hall of Fame; Marilyn Monroe, Babe Ruth, Harry Truman and Pablo Picasso, more recent.Among the unsavory: Jack the Ripper, Billy the Kid and the Boston Strangler.

Despite a rightist world, Neiman says most left-handers feel a certain pride in their specialness."Fortunately for their sakes, lefties generally possess a good sense of humor and an exuberantly healthy ego."

But, claims Neiman, it's up to those who love lefties -- parents, teachers, friends, spouses -- to teach and encourage the reality that "left is beautiful." To empathize with the lefty's plight, he suggests that you:

Try this : Put your wristwatch on your right wrist, set and wind it. Open a locked door with the key in your left hand. Sharpen a pencil, using your left hand to turn the crank. Dial a telephone number with your left hand.

Beware of your own subconscious bias . Don't automatically place a spoon or toy in an infant's right hand. Look for signs of preference -- which hand the child uses to reach for a toy or tool, to eat with, or draw with. Once you've noticed a clear preference reinforce it by handing or placing objects in the preferred hand.

buy tools and products designed for southpaws . A catalogue is available by sending $1 (credited toward first purchase) to Aristera, Dept. WP, 9 Rice's Lane, Westport, Conn.06880.

For a list of about two dozen stores offering lefty products, write Left-Handers International, 3601 S.W. 29th St., Topeka, Kan. 66614. Membership in the organization costs $15 for a year and includes a membership certificate, identification card, 8 issues of The Lefty Letter and 4 issues of Lefty Magazine. CAPTION:

Illustration, no caption, From "The Lefty's Survival Manual"