Ronald Reagan headed West into the sunset today, carrying with him a series of specialized messages carefully tuned to key constituencies in communities he will never visit again in this campaign.

"Coupling," is what a Reagan aide calls it. He is referring not to a rite of mating but to the process of trying to dominate local news coverage by inserting a volatile local issue into the basic campaign speech.

While national attention has been focused on the long-distance campaign between Resident Carter and Reagan ov er whether the Republican nominee is a warmonger, Reagan has been making points on such diverse issues as Cuban refugees, the drought, the energy shortage and natural gas pricing policies.

In Miami, Reagan won the enthusiastic cheers of that city's influential Cuban constituency by denouncing President Fidel Castro and saying that the United States should be a refuge for people fleeing tyranny. A few miles north the same night, to a non-Cuban audience, he repeated these words but stressed that the responsibility for taking care of the refugees should be a national one instead of Florida's alone.

In Springfield, Mo., on Tuesday, Reagan rapped Carter for purported delay in declaring the state disaster area when it needed help because of a drought.

Today, in Tyler, Tex. -- a conservative, oil-rich community in a congressional district narrowly carried by Carter four years ago -- Reagan said that the president was afraid to debate energy policy with him.

Citing government figures that he said showed the inadequacy of U.S. energy production, Reagan said of the president: "He knows his energy policies have discouraged the discovery and production of energy in this country, and that his misleading rhetoric and incomplete facts cannot stand up to the numbers presented in the government reports."

In El Paso, the issue was natural gas policy.

Reagan said here that Carter had "broken a solemn promise" he made to the governors of Texas, Louisiana and Oklahoma in 1976 to "work with Congress . . . to deregulate natural gas."

Later, in Grand Junction, Colo., Reagan told an appreciative airport audience that westerners know how to manage their water resources better than the federal government does.

All of these specialized issues are consistent with the basic Reagan campaign speech and its Litany of "family, work, neighborhood, jobs and peace."

But the emphasis on local interests reflects a somewhat belated discovery by the Reagan campaign that there are ways for a presidential nominee to dominate local coverage by stressing issues sometimes downplayed in the national press. A Reagan aide told this story in trying to explain what was happening.

It seems that the late Hubert Humphrey was addressing a corporate audience. He declared that, contrary to his reputation, he was pro-business because he wanted corporations to make profits that would produce taxes to finance needed social programs.

A weathly businessman in the audience, skeptical of Humphrey, said, "That's all very well. But I bet you don't say the same thing when you meet with George Meany and the AFL-CIO in Bal Harbour."

"If you're saying that I talk more on Mother's Day than I do on Easter, you're right," Humphrey responded.

Reagan also has one message for the faithful and another for those he is trying to convert, the aide acknowledged.

"And I guess that means we're not going to talk about Cuban refugees very much in Provo, Utah," he added. Reagan's statements have received substantial coverage, often eclipsing the world news of the day, in many of the communities he has visited this week. This is partly because he has been stopping in a lot of places where the appearance of a presidential candidate is the big event of any year.

But while Reagan's crowds have generally been large and enthusiastic and while most of the coverage has been favorable, the newfound strategy of "coupling" does not always work..

In Springfield this morning, Reagan's speech of the night before and his standard advocacy of reduced government spending were big news. But the drought was not mentioned until the eight paragraph of the story in the local Daily News. And the newspaper editorially chided Reagan for relying so heavily on standard rhetoric and saying nothing at all about the war between Iran and Iraq.