D el. James H. Dillard (R-Fairfax) is already drafting the political want ads for next year's House of Delegates races in Northern Virginia:

Minimum requirements: Republican. Young. Bright. Moderate to conservative -- the type who can get elected and stay elected. Ultra-conservatives and right-wingers need not apply.

"I hope Republicans learned a lesson this last election," said Dillard, one of eight GOP legislative candidates from Fairfax to win a one-year term in the House of Delegates last week. "The record is pretty clear that the public in Fairfax County is not going to keep Republicans in office that represent the far right wing."

Fairfax County voters pummeled two New Right GOP incumbents at the polls last week: John S. Buckley in Western Fairfax's 50th District and Lawrence D. Pratt in the adjoining 51st District, which covers southwest Fairfax.

Those losses hurt the Republicans, particularly because the county has emerged as a Republican stronghold in recent elections and the GOP was confident it could make even greater gains with the addition of two new seats under the state's redistricting plan.

Instead, Democrats picked up two seats in Fairfax, leaving the GOP with the same number of seats they had when the county had only 10, rather than 12, House seats.

To Dillard and other Northern Virginia moderate Republicans, the meaning of the election is clear: the New Right is a menace to the GOP in Virginia. Outsiders, Dillard calls them. Troublemakers. Many other Republican leaders privately share Dillard's opinions.

"These are not Virginia conservatives," charged Dillard, who joined the GOP when it was largely a movement against the Byrd organization. The New Right candidates, one of whom ousted him from the Assembly in 1977, have no place in Virginia, Dillard said. "They are national far-right conservatives. Virginia conservatives don't respect these people."

Not so, said Buckley and Pratt, who attribute their losses largely to a last-minute infusion of money and political advertisements from a liberal, pro-ERA group's efforts to defeat them.

And they pointed to the victories of fellow conservatives Gwendalyn F. Cody in Northwest Fairfax's 49th District and Frank Medico in Southeast Fairfax's 52nd District as evidence that Fairfax has not slammed the door on very conservative Republicans. Other Republicans counter that Cody and Medico, both elected to their first terms in the House, aren't identified as part of the same national New Right network as Buckley, a cousin of conservative columnist William F. Buckley, and Pratt, executive director of Gun Owners of America.

But the two New Right delegates weren't the only incumbent fatalities of the fall elections for Northern Virginia Republicans. They lost a moderate in Alexandria, first term incumbent David Speck, and a party maverick in the primaries -- Martin Perper in Fairfax's 49th District.

And while the Republicans picked up eight seats in the House statewide, Northern Virginia, heavily targeted with GOP campaign money, contributed only one additional seat overall. Northern Virginia will send 11 Democrats and 10 Republicans to the General Assembly in January: a one seat-gain for each party compared to the current 10-9 tally in the Democrats' favor.

The Republicans did score a substantial victory in the Loudoun County 17th District, where Republican Kenneth B. Rollins captured Democratic incumbent Earl E. Bell's seat.

"The pendulum keeps swinging," observed state Sen. Wiley F. Mitchell (R-Alexandria). "A year ago it was a good time to be a Republican. This past election was a good time to be a Democrat. I don't know where it will be a year from now."

There was no better place to be a Democrat this year, Republicans say, than in Alexandria's 21st District, where Republicans were stunned by the defeat of one of their most popular delegates, first-term incumbent Speck.

If the losses in Fairfax County were chalked up to lessons learned the hard way, Speck's defeat was attributed to a more tangled set of circumstances: the strong Democratic sweep of the statewide elections and the voting power of young government bureaucrats, blacks and senior citizens protesting the Reagan budget cuts that have filtered down to their pocketbooks.

"Speck was inundated by a strong Democratic vote in Alexandria," said Dillard. "When the statewide (Republican) candidates went down in flames, he was caught in the conflagration."

Almost 5,000 more voters than expected turned out at the polls in Alexandria last week, according to Republican strategists.

"Many of them came to the polls for the purpose of sending a message across the Potomac River rather than selecting among individual candidates," Mitchell said. "I doubt if any Republican candidate in Alexandria last Tuesday could have survived."

This year's Republican problems may be a foreshadowing of even more headaches next year, some GOP partisans say. They concede many party members and supporters have been demoralized by this year's Democratic siege.

"Getting wiped out is quite a blow to the Republicans," said Del. Vincent F. Callahan Jr. (R-Fairfax), successful in his bid for reelection. "I think we've been hurt, there's no question, but I still think we are strong. Maybe we got too overconfident or too fat winning all those elections in the past."

Yet Callahan acknowledged, "It gives Democrats an edge next time. It's always good to have a friend in the governor's mansion."

Republicans admit they don't know where they will turn for a party spokesman in next year's election. Most Northern Virginia Republicans say that the party's unsuccessful state attorney general candidate Wyatt B. Durrette Jr. of Fairfax, who narrowly lost, will remain a strong party leader.

The national party leader, President Reagan -- the man who just over a week ago was considered one of the Republican's greatest assets in Virginia -- became a political albatross in some districts. And some GOP officials fear he could be an even greater burden next year when the 100 members of the House face another election after a court-ordered redistricting.

"So much of what happens here is a reflection of what happens in Washington," noted Mitchell.

"If the economic picture is not rosy next year ," he added, "we're going to have to do a better job than this election in explaining to people exactly what the Republican Party on the national scene is all about."