There's help for the traveler in new publications designed to aim tourists in the right direction in the United States, take the mystery out of ordering meals in a number of foreign lands or facilitate communicating with a foreign doctor in his own language - even if you don't understand it.

National Geographic, which says it has "packaged America," is offering 16 large full-color, plastic-coated maps of the United States (15 regional and one of the entire country) with a hardbound, 200-page index, additional facts and figures, and a plastic filing case, to nonmembers and members alike.

Price is $19.95 until May 31, when it will rise to $23.95. The vacation package is available at the Explorers Hall sales desk at the National Geographic, 17th and M streets NW. or by mail from the National Geographic Society, Dept. 100, Washington, D.C. 20036.

William E. and Clare F. Marling, who explain that they began in 1969 to collect menus from restaurants of all classes in France, Italy, Germany and Spain, first published their set of four guides to ordering foreign foods. "The Marling Menu-Masters," in Europe. Now the books, one for each of the four countries mentioned above, are being "imported in quantity into the United States" to enable travelers "to translate rapidly and accurately into English" those strange-sounding and often unpronounceable dishes.

Ths slim (around 100 pages) pocket-sized books are available by mail at $2.65 each from Books, Rough and Ready, California 95975. They also are supposed to be in stock soon at major bookstores.

If you happen to become ill overseas (but not as result of a restaurant meal, heaven forfend), the Medical Economics Co., Box 554, Oradell, N.J. 07649, has a dandy little item that might quicken your recovery. "The Worldwide Medical Interpreter," by George B. Settar (160 pp., $7.50 per volume), is designed to enable physicians, dentists and others in the health field to communicate with patients who speak a different language.

Volumes in English, Italian and Greek are now available. All are interchangeable, "page by page, questions for question, answer for answer." Thus, "by nodding 'yes' or 'no' and pointing to the numbered questions and answers (in separate books), the doctor and patient can easily conduct a two-way dialogue."