Travel in eastern Europe and the Soviet Union takes careful advance planning. For example:

VISAS: Unlike going to western Europe, where only a valid U.S. passport is needed, you must have a visa for each eastern European country, and getting them often takes time. Hungary is easiest for tourists (even officials at the border will issue a visa), the Soviet Union the most difficult (especially if you have relatives there or plan to visit any Soviet citizens). Usually you must have tickets and hotel vouchers in hand to get visas.

It is a good idea to get help from a reliable travel agent who is especially knowledgeable about eastern Europe. Your agent can provide visa forms and customs declarations, and help you fill them out, and will plan your travel and hotel arrangements, working with the official government travel agencies: Intourist in the Soviet Union, Orbis in Poland, Reiseburo in East Germany and Ibusz in Hungary.

CURRENCY: Communist countries want you to spend dollars -- they need them badly -- so they'll let you use American credit cards at the official rates of exchange. The value of the dollar doesn't fluctuate in eastern Europe the way it does in the West, but we found prices last year quite reasonable for Americans. Also, while you're far more likely to be robbed in Paris than in Warsaw, it still pays to watch and protect your money, tickets and passports.

BAGGAGE: Pack the minimum possible; nobody in eastern Europe dresses fancy. Figure on no more than you can handily carry because the labor shortage precludes porters and there are lots of stairs. (Nor are there any conductors on streetcars, buses or subways.)

The exception is the Soviet Union, where Intourist meets you, helps with bags, has a car or bus to get you to your hotel and can get you taxis. But don't count on hurrying; everything, even getting a meal, takes more time than back home -- though fast food is creeping into all countries and the increased number of tourists has forced a cut in paperwork for travelers.

FOOD: We never encountered a railway dining car, though porters can provide mineral water, soft drinks (usually very sweet), tea and maybe coffee for a small fee. The porter keeps them stashed away in his compartment and you'll see people traipsing back and forth to buy. We found this the best routine: At breakfast in your hotel -- often the best meal of the day -- pick up extra bread, rolls, butter (in foil packets), salami, havarti or other good cheeses, hard-boiled eggs, pickles and jam.

Pack plastic bags and utensils from home, and before you board the train buy a bottle stopper (European sizes may be different from American but their stoppers also are bottle openers). Those airline miniature salt and pepper containers also are worth taking along. For napkins, besides those from breakfast, you have the numerous small packs of tissues without which you wouldn't travel. Remember, the train toilets are likely to run from unsanitary to filthy. Train water is not potable.

GUIDEBOOKS AND MAPS: Unless you're satisfied with skimpy city maps and propaganda pamphlets, take your own maps and travel information.