IT'S BEEN said before, that the only way to learn is to practice. Fortunately, this applies even when the skill involves wine. For beginners, as well as for those who can detect the leaves and stems in a new cabernet, wine classes are the best way of practicing, of fine tuning that palate.

There are a variety of area classes--from introductory classes to educational seminars and tastings--covering just as many topics--which may be divided by grape variety, price or country. Classes vary in tone, too. Last year, students at Open University chatted and sipped chardonnays on instructor Ron Ludin's living room couch, while at the American Academy of Wine, the tasting room was silent and serious as students sniffed and swirled each glass of bordeaux.

A newcomer to wine should start with an introductory course. Most important, you will learn what kind of wines you like, as well as some practical matters such as how to read a wine label (and thus better shop in a wine store) and how to choose wine at a restaurant.

The introductory approach is learning how to taste, rather than zeroing in on a particular region or grape. In the first of the three-part introductory series at Mayflower Wines, for instance, students learn the elements of wine by sipping water-based solutions of sugar, alcohol, acid, vinegar and tannin. After that, they graduate to swirling wine in a glass and swishing it in their mouths, and on to a session each in whites and reds.

Having learned how to taste, even beginning students can partake in tastings, enabling them to taste a range of wines that, for either cost considerations or preference, they might not ordinarily purchase. The classes can be structured in several fashions, determined by the instructor. Participants either know what they are tasting, or they don't. When what's what is known, the tasting may take the form of an educational seminar with information on the wine region, its history and a glossary of terms. At a blind tasting, each place setting may consist only of a tasting sheet and 10 glasses filled with an inch of wine. The former type of tasting is more appropriate for those who want to learn the basics; the latter is usually frequented by more advanced students.

In any class, expect to taste an average of eight wines (some places also have cognac and beer tastings, too, and a past Mayflower Liquor beer tasting went into the night with 40 brands). Cheese, bread and maybe pa te' are included, although not emphasized (purists argue over the intrusion of food when tasting, since cheese makes wine taste better). A surprise may be thrown in for dessert, like the cake served last year to complement the Fontanafredda Asti Spumante at a Harry's Liquor Italian wine seminar. Unfortunately, some teachers do not suggest food accompaniments as you taste, but others, like those at Mayflower and Harry's, are more concerned about culinary aspects; that sauvignon blanc goes well with swordfish and bernaise, this Fagnano Chianti Classico is good with lamb.

A warning: Keep the teachers' commercial affliations in perspective. If a wine store staffer is leading the class, be aware that some pricy wines that the store may be hoping to sell tasters may appear on the tasting list. (As many wine professionals have said, the price of a wine doesn't necessarily correspond to its value or taste.) And obviously, laudatory remarks on a wine should be kept viewed with some skepticism if an importer or vineyard representative is the guest lecturer.

In addition to classes open to the public, there are tastings sponsored by area wine clubs and open only to members. Here is a sampling of this year's crop, open to all:

American Academy of Wine. (202) 362-0768. Owned and operated in conjunction with Wide World of Wines. Two-part introductory classes, professional classes, tastings frequently led by guest speakers. Classes start Sept. 20, 7-9 p.m. From $15 to $35. Mayflower Wines and Spirits. (202) 463-7950. In Northwest, fourth year of three-part introductory class starting first week in October ($52). First year of three-part intermediate class, starting Sept. 26 ($100).

Mount Vernon College. (202) 331-3539. Hamilton Mowbray teaches his 10th year, this year featuring the wines of Burgundy. Wednesdays, Sept. 21-Nov. 9, 7:30-10 p.m. ($75).

Open University. (202) 966-9606 or (703) 250-2520. Ron Ludin teaches his fifth year with Open University, now in Northwest. Three-part introductory classes ($45) starting Sept. 28 and Nov. 22. Tastings start Sept. 16. $16 to $21.

Round Table Wine Tasting Seminars. (202) 783-4200 or (301) 952-0545. Associated with Harry's Liquors. Sixth year in Southeast. Tasting seminars from Sept. 12 to March 12, starting at 7 p.m. $15 to $25.