The February cover of Life seems appealing enough. On the bottom is a large color photograph of an attractive woman in a bathing suit. Above it is a smaller black and white portrait of John Lennon and Yoko Ono. A newstand browser might casually assume this reflects the current cruisewear season and a lagging monthly's attempt to pay tribute to the slain Beatle.

In fact the compound image might be considered the state of the art in the strategy of selling magazines. In an industry so dependent on impulse buying, purchases are invariably determined by monentary glimpses of covers. The careers of editors and art directors alike -- not to mention the corporate profits of publishers -- rise and fall with the success of covers.

Last December, virtually every magazine that put John Lennon on its front experienced a publishing bonanza. Time sold more than 500,000 copies on newsstands, topped in the past 30 years only by the resignation of Richard Nixon and the Jonestown mass suicide. Newsweek sold about 450,000 copies, double its usual newsstand take. The issue was the second-best seller in the history of the magazine, exceeded only by the Nixon resignation cover. New York and People both registered the largest weekly sales in their histories, respectively moving 60,000 and 2.6 million copies.

The annual bathing suit titillation of Sports Illustrated -- on the stands this week -- is a perennial best seller, so successful that year-old Inside Sports has its own "Famous Annual Bathing Suit Issue" on sale this month. s

Now they're certainly not dummies at Time, Inc. So they take bathing suits and John Lennon and . . . PRESSTO! You can bet the February issue of Life will sell plenty.

As the noble Jesuits wisely counseled their flocks, sex and death are two of the eternal verities. Besides John Lennon, the huge hits of 1980 were Bo Derek, Suzanne Somers and Valerie Bertinelli. Derek and Somers were neck and neck, so to speak, as the big winners for Playboy. Derek also graced the best-selling issue of McCall's. A leggy shot of Bertinelli did so well for Us in February (selling 830,000 copies) that the publishers decided to do it again in November. This time she sold 850,000 copies. An intimate portrait of Steve and Cyndy Garvey (his hand is grabbing her posterior) scored best for Inside Sport.

If brides qualify as sex symbols, it is easy to understand the best-seller status of Esquire's December "Looking for a Wife" cover, featuring a bride who certainly seemed hotter than most. Newsweek's third-best seller was on teen-age sex, exceeded only by Lennon and a thorough reporting job on the hostage rescue attempt aborted in the desert. With the exception of its annual off-the-charts fall preview issue, TV Guide, the largest-selling magazine in the world, did best, with a cover on steamy old "Dallas." Even the gothic Reader's Digest triumphed with a supermarket cover band that announced: "How To Trim Your Hips and Shape Your Thighs." And, naturally, the National Lampoon's May"Sex," says editor Gerry Sussman, "is sex." Which may explain the delicious February issue out now, on the theme of sin and loaded with . . . sex. On an even more literal level, Penthouse's best was a striking shot of Blondie's Debbie Harry: "Sex Symbol of the '80s."

Only Redbook slumped in the sex department. The clunker of the year was its February issue, which included these three cover lines: "Talking About Sex; Advice to Couples Who Want a Baby; Dustin Hoffman: Outrageous and Sexy."

Other big winners and losers of 1980:

Brooke Shields was People's second-best cover, with a slinky shot from her film "Blue Lagoon." Third best was a July "Who Shot JR" number. Paul Simon was the hands-down worst at People, followed in order by The Who and a montage from the movie Airplane.

The eruption of Mount St. Helen' ranked second-best at Time, followed by a post-election cover on the victorious Ronald Reagan. Oddly enough, a March cover on Reagan was the flatout loser for Newsweek, barely exceeded in sales by two cover -- one in February and another in April -- that predicted a breakthrough in the hotage situation. Time's worst-selling cover featured Jimmy Carter back in March. Second-worst was a story on Detroit, followed by a profile of Ed Muskie.

At Sport Illustrated, the triumphant U.S. Olympic Hockey Team closed rank behind Christie Brinkley's bathing suits. SI's worst issue touted golfer Steve Ballesteros, less known in the world of the living than even Bruce Springsteen. Anyway, SI's annual golf issue is almost always its big loser. Inside Sports' worst was a cover featuring two Confederate flags and tales of the South. "The absolute bomb of the year," says publisher Dan Capell, "probably because it was our only attempt at nonsports."

Life triumphed with an old sepia photograph of old-time screen star Mary Astor; it stumbled with a photo of the Cape Hatteras Light House that looked more like the neck of a mutant zebra. Incidently, last September Life managing editor Phil Kunhardt invited readers to choose their favorite covers from the monthly's first two years of publication. Khomeini was the hands-down loser; a whale's tail and an eclipsed sun received equal numbers of voters as best.

Hypnotism backfired at Washingtonian last April. A cover on the legitimacy of hypnosis featured a pretty woman and the proverbial swaying pocket watch, with a cover line: "You Will Buy This Magazine, You Will Buy This Magazine, You Will Buy This Magazine." Only 19,384 readers did. Conversely, a provocative "Who Killed JFK" cover, replete with frames from the Zapruder film, sold 34,416 copies.

Men did poorly on many covers. At Us, for instance, virtually no cover featuring a male sold as well as any offering the other sex. The big bomb at Us was John Schneider, who plays Bo Duke. TV Guide's worst touted Gregory Harrison and Pernell Roberts of "Trapper John, MD." Jimmy Carter was New York's clinker. Actor John Wayne flopped on Esquire. And actresses (can we really include Bo Derek and Suzanne Somers in this in this category?) fared no better. Meryl Streep graced the worst-selling issue of Ladies Home Journal, while Jill Clayburgh bombed at McCall's.

The New Yorker's best seller of September 29 had a Gretchen Dow Simpson cover of three men on a tenement stoop, and included the first installment of Thomas Whiteside's tripartate exigesis of the book-publishing industry. The loser of the year came three weeks earlier, wrapped in a Paul Degen sketch of a clown and containing yet another Elizebeth Drew piece on the presidential campaign.

At New West, the winner was a look at Big Sur; Texas Monthly's, a look at the King ranch. Rolling Stone scored best with the singer and lead guitarist of the band of the plural form, and worst with Bob Hope.

Business types will want to note that Forbes did best with a cover on Delta airlines, and worst with a painting of moneyman Fayez Sarofim. Business Week's best was a post-election Ronald Reagan cover; its worst a cover on bad luck at Lloyd's of London. And with the exception of its annual Fortune 500 issue, Fortune scored best with a profile on the Hunt Brothers and sold its fewest copies when a tattooed coal miner graced its cover.

Omni's best was a cover on human evolution; its worst: "Russia's Iron Grip On the High Frontier," strangely illustrated with a butterfly atop a safety pin.

At The National Enquirer, the year's worst came with: "Surprising Secrets of How to LIVE LONGER from over 1,000 Who Have Lived to Over 100." The best: "Michael Landon and Wife Split."

Cosmopolitan's biggest-selling cover was cool blue in August, and included these cover lines: "Dealing with Anxiety. You Can Do Something" and "A Zodiac Guide to the Men in Your Life. Come on, Now! It's Fun!" The worst was hot pink in November, with these stories touted: "What Today's Bold New Women Are Doing to Men" and "The Wondrous World of Sissy Spacek, a Whole New Kind of Movie Star."

Savvy's premier (January) issue sold best, with businesswoman Nancy Englander on the cover; worst was a May cover painting of Jane Cahill Pfeiffer, who was soon to be dumped as NBC's chairman of the board. Ms. also did best in January, with a sunny cover titled "80 Women to Watch in the '80s." The worst: a stop sign, with this cover line: "The Leadersship Crisis in America, Are Women the Answer?"