What's up? The dollar, oddly enough. Between January 1980 and April 1981, it's risen a spectacular 38 percent in Greece, 31 percent in Italy, 24 percent in France. Even in Mexico, it's up 4 percent, in Canada 2 percent.

Before streaking for foreign parts, though, the U.S. State Department recommends you pause to learn one or two other "practical" things -- like the currency regulations where you're going.

The only trouble is that getting a straight story on regulations plus foreign exchange rates and foreign exchange practices, particularly in places other than Western Europe, may be nothing short of hairy:

If you want to know currency rules for Egypt, you might well call the Egyptian Embassy in Washington. I did. Three times. According to one person there, visitors cannot bring in or take out any Egyptian currency. On my second call, I was told you can take in or out any amount you wish. On my third call, the official word was that you can't take in any Egyptian currency and must charge $100 at the airport as you arrive.

For my fourth call, I tried the Egyptian tourist office in New York. The version there: You can take in 20 Egyptian pounds and must change $150 at the airport on arrival if you're traveling on your own but not if you're part of a tour group.

How about Israel? The first bank I called explained I could take in no more than 1,000 shekels and would be better off buying them there, where I would get about nine to the dollar. According to a second exchange dealer, I could take any number of shekels into the country and would do "about as well" buying them here at their "very competitive rate" of 6.6 to the dollar.

A spokesman for the State Department was adamant: Visitors are not allowed to take in any Israeli currency. Not 10 minutes later, El Al, the Israeli airline, assured me I could take in any amount I wished and that the "most recent rate of exchange in Israel has been 9.5 shekels to the dollar.

To buy Braziliana cruzeiros on April 18, the exchange firm that calls itself the oldest and largest in the United States, Deak-Perea, quoted selling rates of 66.67 to the dollar at its Washington, D.C., office, 75 to the dollar at its New York office, 77 to the dollar in Miami. No one mentioned that the official rate had been "adjusted" two days before and you could buy cuzeiros in Brazil at 79.48.

Yes, said the foreign trader for one bank, "basically you get a better rate abroad for dollar traveler's checks than you do for dollars." Oh no, said another, "you get a better rate abroad for the dollars than you do for traveler's checks."

Confused? Clearly you're not alone. But why worry? Well, in the exchange game, there are at least three "worst case" possibilities: (1) You might well sacrifice anywhere from a 5 to 50 percent saving if there's an openly tolerated black or "parallel" market in a country that you learn about too late; (2) you can lose more than a little if you swap, say, $20 at a time instead of a large amount, only to discover you are paying $1 to $3 per transaction, the case in many parts of Europe; (3) you can blow as much as $5 or $6 out of each $50 by indiscriminately changing money and not knowing there are good places and bad.

Or, skip to a typical case:

Let's say that the Hypotheticals are off to England. They're experienced travelers and appreciate the safety of traveler's checks. They therefore drop in at their friendly neighborhood bank and buy a bundle. In Britain, they dole them out as needed, careful to change only at banks becuse they know that hotels, restaurants and 24-hour exchange shops give abysmal rates. Later they tally up their costs: They've spent about $1,200 -- dropped roughly 5 per cent, $60, just on currency transactions.

Could even they have done better? Most likely, yes. First of all, lots of people pay one percent for their traveler's checks when they don't really have to. Around the nation, some banks offer free dollar checks; some auto clubs also come through. And Deak-Perea currently issues free VISA traveler's checks.

We'll also assume the Hypotheticals assumed that all banks in Britain use the same exchange rate. They don't. The rate published daily in newspaper foeign-exchange tables is a wholesale rate and in Britain, as here, banks and others who sell money make their own retail rates.

Moreover, most banks there tack on "minimum" commissions as well, fees that lately have run between about $1.10 and $2.20 for each transaction.

Such disparities mean comparative shopping is meaningful. But sightseeing British banks hardly makes anyone's list of "golden moments." Alternatives: shopping for pounds at home, shopping for pound travelers' checks at home, using plastic money.

Using plastic -- credit cards -- is the easiest and cheapest, since all the major companies convert foreign charges at the "wholesale" interbank rate. American Express, though, tacks on a one-percent service charge; the others do not.

However, merchants can be slow in sending in charge slips, and since you're billed according to the interbank rate on the bank or card company processes the transaction, the rate could be higher or lower. But if things work dramatically against you, protest; adjustments can be made.

Credit cards, though, aren't too useful to budget traveler's, since they're mainly honored at pricier places, just as dollar traveler's checks sometimes aren't as handy in the countryside as they are in the large cities. We therefore come to Jane's Law: The only substitute for money is time.

For me, then, it's hike to the library, read old Wall Street Journal exchange tables and see which way pounds (or whatever) have been moving, for how long, and what's considered likely. I look at guidebooks, too, for helpful hints, any mention of odd doings in money matters where I'm going. I then try to figure our why, if the State Department people want us to know currency regulations abroad, they don't just arrange to tell us.

Eventually I compare what I've learned to what I hear when I question exchange companies, banks, tourists offices; if I'm a client, I have the added opportunity to check and recheck with my travel agent. But I don't buy any money unless my sleuthing and shopping turn up an extraordinarily good reason: for instance, traverler's checks denominated in British pounds or whatever else I need, selling for less than 2 percent above interbank rates (it does happen).

Generally, I gauge my needs and leave with a mixture of credit cards, personal checks, cash and commission-free traveler's checks -- more cash than checks for the Third World, more checks than cash for highly industrialized part.

It may not be the best of all possible systems, but it works. Money-shopping abroad istn't too bad, and there just may be a bonus: You sometimes meet the nicest people standing in exchange lines.