House Democrats, meeting in an upbeat mood as they contemplate the end of a political era that has been dominated by President Reagan, were warned today against initiating tax-increase proposals to reduce the federal budget deficit.

That advice came from a bipartisan group of political consultants who addressed a weekend meeting of the House Democratic Caucus at the exclusive Greenbrier resort here.

House Republicans, meeting at a similar retreat in Baltimore, were given a similar message by a key GOP pollster, Robert M. Teeter: Don't get mired down in trench warfare over cuts in specific programs, such as student loans, Amtrak and Medicare.

"If we end up debating those issues all year, we're not going to have a very good year," Teeter said.

Both conferences were dominated by talk of strategies to deal with the new Gramm-Rudman-Hollings balanced-budget law and for the 1986 congressional elections.

The message the Democrats heard here was that their prospects are on the rise, but that the deficit and tax issues remain fraught with political danger.

When House Budget Committee Chairman William H. Gray III (D-Pa.) asked whether Democrats should "push forward" with revenue proposals to cut the deficit, David Doak, who helped engineer Virginia Gov. Gerald Baliles' successful campaign last year, replied:

"In 1984, we had a national referendum on that and we lost 49 states. My feeling is we should steer clear of that."

At the same time, another Democratic consultant, William Schneider of the American Enterprise Institute, urged the Democrats to find a way to avert the major, automatic budget cuts due to be made on Oct. 1 unless Congress and the president agree on an alternative deficit-reduction program.

He said those cuts will produce "a sense of anger" around the country and that "the public will say Congress created the crisis."

Schneider said recent polls suggest that the public is willing to accept some higher taxes to reduce the deficit, but he agreed with Republican consultant Kevin Phillips, editor of the American Political Report, that the initiative should not come from the Democrats.

The House Democrats met on the same day that Reagan announced the first round of automatic Gramm-Rudman-Hollings cuts that will be imposed on March 1. Those cuts are limited to $11.7 billion, but the second round, to reduce the fiscal 1987 deficit to $144 billion, is expected to be at about $38 billion unless an alternative is found.

The consultants' somewhat contradictory advice -- to seek a compromise on the deficit without calling for higher taxes -- was well received by the House Democrats, whose leadership has is trying to force the White House and Senate Republicans into making the first move toward higher taxes to avoid the automatic budget cuts.

After Reagan submits his budget to Congress next week, the House Budget Committee plans to hold a series of hearings around the country designed to show that his expected call for deep domestic spending cuts but no new taxes represents "a failure of leadership."

"The bottom line is that we have to participate in the process" of finding a budget and tax compromise, said Rep. Leon E. Panetta (D-Calif.), a member of the Budget Committee. But, "utlimately we will have to come up with revenues."

This was the second year that the House Democrats have met here and the first time the conference was open to the news media.

Conference organizers said they expected the cost of the meeting to be about $200,000, with well over half that amount being provided by corporate contributions to the National Legislative Education Foundation.

The 106 House members who are here paid $400 each to attend the event.

Looking toward the 1986 congressional elections and the 1988 presidential contest, Phillips told the conference that the rise of the conservative movement as symbolized by Reagan is now in "late middle age," not its infancy as many Republicans hope.

He and Schneider also said that the growing importance of right-wing religious leaders in Republican politics poses a serious problem for the GOP and could force the party's presidential hopefuls in 1988 too far to the right during the nominating process.

House Republicans at their Baltimore meeting were told that they should cling to the political advantage of economic recovery and Reagan's popularity rather than deal with specific program cuts.

Teeter, the GOP pollster, also urged Republicans to unite as soon as possible on a strategy for complying with Gramm-Rudman-Hollings. "The sooner we can come to a united Republican position, if possible, the better off we'll be," he said in comments echoed by other party chiefs including House Minority Leader Robert H. Michel (R-Ill.) and Whip Trent Lott (R-Miss.).

But the difficulties for House Republicans were underscored as factions within the party aired disparate approaches to budget cutting and a move was launched to draft an alternative to the intial automatic cutbacks due to take effect March 1 under Gramm-Rudman-Hollings.

Party leaders considered such a proposal from Rep. Beau Boulter (R-Tex.), who said the only support for allowing the automatic cuts to take effect comes from those who want to blame the GOP for the pain of the cutbacks and to "see Gramm-Rudman unravel."

But enthusiasm for the proposal was mixed. Asked how it squared with Teeter's advice, Lott said, "Nobody said we're going to do it."

The conference drew only about 35 of the 182 Republican House members, but Michel and others exulted in contrasting the GOP meeting in "blue-collar Baltimore" to the Democratic meeting at the Greenbriar. "I guess they the Democrats expect to find their future in the ambiance of sumptuous luxury at that upper-class resort," Michel said.