It was rugby that got John R. H. Cotter into publishing.

As a University of Maryland undergraduate, he played on the varsity team and kept active in a Washington league after graduation. "I've played rugby for the first 25 years of my life," he began to think. "Within a couple of years, I want to be doing something different."

But what did he know? "Nightlife." When you play rugby regularly, explains Cotter, now 32 and living in Greenbelt, "you party a lot."

He decided to "walk around town and research places." After about eight months, and with some writing instruction from a former English professor, he put together a manuscript. "I learned to write doing that first book. I wrote everything in it at least three times."

At that point, he figured a publisher would want to keep a large chunk of any profits, "so I decided to do it for myself."

In 1980, he published the 200-page paperback first edition of Nightlife: Wash. D.C. & Metro Area. The book sold originally for $4.95. About six months ago he brought out a second, and much larger, edition (by almost 100 pages) that sells for $3.95. "I got a better deal in printing."

Cotter says he was lucky when it came time to distribute his books, often a major hurdle for small publishers. The District News Company agreed to put it in magazine newsstands in grocery stores, drug stores and hotels throughout the city.

Still, he says, "It didn't make me a bundle. It did medium well. I made a couple of thousand on the deal." For the second edition, he had 15,000 copies printed, "and it's going pretty well, even though it hasn't been through a tourist season yet."

Printing and typesetting, he estimates, cost about $15,000 for the latest edition, or $1 a book. Newsstands and the distributor will take a substantial bite of profits, so unless the guide really takes off his potential profits are anything but spectacular, especially after figuring in the cost of his labor. New editions, however, could keep a steady sum coming in.

Meanwhile, Cotter has published two editions of a guide to Ski Resorts Within 5 Hours of Washington and Baltimore, which have added to his income. Although figures aren't all in, he thinks he may have come close to selling 75 percent of the 30,000 copies printed for the past ski season. The 96-page booklet sold for $2.50 and cost him about $15,000 to produce, not counting distribution costs. In the works is a magazine as his Entertainment Research publishing firm grows.

At the moment, though, "I'm eking out a living. I eat a lot of pizza these days. I'd recommend not writing a local book and trying to make a living off of it." On weekends, he does wedding photography. And just the other day, he signed on as a part-time evening waiter on the restaurant cruise ship "Dandy" out of Alexandria.

Nonetheless, "I never enjoyed myself more."