In reminiscent moods, President Reagan is fond of recounting how he settled a contract for the Screen Actors Guild during a chance meeting in the washroom with the negotiator for the other side.

More than three decades later, the president who is often called "the Great Communicator" prefers to think of himself as a great negotiator.

"You don't see a lot of pride expressed by Ronald Reagan, but in this area he takes pride," says Reagan intimate Michael K. Deaver, the president's deputy chief of staff. "He thinks of himself as a negotiator, and he knows when to compromise."

Over and over, as labor negotiator, governor and president, Reagan has followed a time-tested pattern in bargaining with his adversaries.

He takes a firm stand at the outset, refuses to make concessions in advance, keeps his bargaining cards close to his vest and strikes a compromise only when the negotiation is in danger of being lost.

As in almost every other aspect of his presidency, Reagan sets down these broad principles and then delegates the detail work to a few trusted aides.

The president's negotiating skills are likely to be tested sorely in the weeks ahead as the administration tries to push ahead against domestic opposition on the defense budget, aid for El Salvador and the MX missile, and internationally for an interim agreement with the Soviets on reducing intermediate-range nuclear weapons in Europe.

Already, however, outlines are emerging at the White House pointing to the familiar path of negotiation and compromise that Reagan has trod before in eight years as governor of California and more than two years as president.

On the defense budget, for instance, senior administration officials recognize privately that Reagan will have to settle for less than the 10 percent real growth he is seeking in Pentagon spending. Senate Republicans are talking about a 5 to 6 percent increase, and the House has passed a budget resolution providing even less.

These increases, however, come atop massive defense budget increases during the first two years of the Reagan presidency which provided far more for the Pentagon than the 5 percent real growth that candidate Reagan promised in the 1980 campaign.

On El Salvador, there are whispers in the White House that the administration's aid requests are grossly inflated and designed with the knowledge that Congress is determined to cut them.

Whatever happens on these issues, Reagan already has achieved more than many would have thought possible a few months ago with a restive, if Republican, Senate and a House controlled by the Democratic opposition.

The widely ballyhooed compromise on Social Security, an issue that has been political poison for Reagan, takes more in cost-of-living cuts than it imposes in new taxes.

The $4.6 billion jobs bill is a compromise on administration terms, relying chiefly on acceleration of previously approved projects and appropriating relatively little new money.

While dealing with the Russians is more difficult than dealing with Congress, the Reagan pattern is similar. For weeks Reagan resisted the call of Republican moderates at home and U.S. allies abroad to move off his "zero option" proposal for removing all intermediate-range nuclear weapons from Europe.

But next Thursday before the Los Angeles World Affairs Council the president will offer a revised proposal, aides say.

Reagan gave a glimpse of his philosophy recently in a White House interview where he was responding to a question about Middle East negotiations.

"I don't take too seriously the statement of positions in advance of negotiations," the president said.

"Everyone wants to preserve their position at their highest price before negotiations. And for them to do otherwise is to give away something they might have to give away once the negotiations start."

White House officials say that Reagan, who sometimes seems out of touch with or removed from issues which involved other presidents in great detail, becomes highly involved when a negotiation is in process.

But this involvement tends to be a matter of political intuition and concern for the ultimate outcome rather than of bothering with details.

The negotiations that led to the Social Security compromise, for instance, were carried out without the president by a White House team consisting of chief of staff James A. Baker III, presidential assistant Richard G. Darman, legislative liaison Kenneth M. Duberstein and budget director David A. Stockman. For the most part they preserved what one White House aide called "the interesting fiction" that Reagan wasn't involved, which was meant to be a convenient escape hatch if the negotiations collapsed.

In fact, Reagan approved various opening positions for the negotiations, was briefed after each session and played a shaping role in the final compromise. On the Saturday on which the package was agreed to, he asked the key question, "Has the speaker signed on?"

When Reagan was shown a draft of House Speaker Thomas P. (Tip) O'Neill Jr.'s comments agreeing in advance to the package, he commented simply, "Our strategy has worked."

Many credit the administration's negotiating achievements on difficult legislation to the skill of the White House team, especially Baker. But Reagan followed a similar course in California, where his chief negotiator was usually Edwin A. Meese III, now the White House counselor.

"What any administration values is usually what the president values," said one aide. "This president values negotiation--and good negotiators."

One of the principal reasons why Baker wound up as White House chief of staff after working for Gerald R. Ford and George Bush is that Reagan was impressed with Baker's skill in arranging a debate with Jimmy Carter.

Sources close to the president say he particularly admired the audaciousness of Baker's opening position, which was to have the debate the day before the election.

Those close to Reagan have identified basic patterns of his negotiating position. They say he never makes preemptive concessions, operates in a spirit of good faith with respect for his opponents and their offices, states his own positions with clarity and knows where he wants a negotiation to come out.

"He doesn't get us into a position of compromising with ourselves," said Duberstein. "He sets very firm principles, knows where he wants to go, knows before we go into a negotiating position where the votes are, knows that if you demonstrate any weakness with the legislature or the Congress that a little opening becomes the floodgates. He also has an uncanny sense of timing."

Reagan's view is to make the other side reveal its positions early and keep his own hand hidden as long as he can.

"I've heard any number of times about the importance of not revealing your tactics, laying out a very clear position early, letting the other guy come forward and striking the best deal you can get," said David R. Gergen, the White House communications director.

Early this year Reagan resisted a clamor from Capitol Hill, some of it orchestrated by key Republican senators, that he agree in advance to a compromise on the defense budget.

When Stockman, also a formidable negotiator, made a suggestion that a compromise defense budget be sent to the hill, Reagan rejected it, agreeing in advance only to a military pay freeze as part of a larger package.

"He knew the defense rollback was coming," says an aide. "He knew that it would be more, not less, if he caved in ahead of time."

The administration's greatest difficulties arise when Reagan departs from his customary strategy of negotiation. Last December, for example, the administration suffered a stinging defeat on the MX missile because neither the president nor his chief aides correctly estimated the degree of congressional skepticism and the symbolic importance of this missile system and declined to offer a compromise until it was too late.

Nonetheless, it might be said that Reagan's great dream is a negotiator's dream--one of a genuine strategic arms reduction agreement with the Soviets that would be almost certain to be ratified by the Senate.

Reagan has often talked in private, and occasionally in public, about going down in history as the president who pulls off this achievement. If he succeeds in this improbable task, administration officials believe, it will be because he borrowed the principles of his Hollywood negotiating days and used them in the international arena.