The Republican National Committee is going to "grade" and then try to improve its state and county organizations in targeted areas this year in preparation for the 1984 battle to preserve GOP control of the White House and the Senate.

Party Chairman Frank J. Fahrenkopf will lay the ambitious plan before the party's executive committee today and hopes to get it under way within 30 days, he said in an interview yesterday.

Regional GOP political directors and party officials of each state will evaluate organizations on their capacity to finance candidates, target voters and conduct other basic election activities, and give each state a grade from 1 to 10.

The grades will be combined with a priority scale based on the importance of the state in presidential politics and the presence or absence of a critical 1984 Senate race, to select between 25 and 30 states for intensive improvement by next March.

In each selected state, the same measure and effort will be applied to the five or six most important counties, Fahrenkopf said.

The effort will be carried out by the RNC field staff, which is being expanded to at least 40 people. Fahrenkopf said he was cutting back on some headquarters operations and publications in order to finance the expanded field effort from the $21 million budget he inherited when he took over the chairmanship in January. Some firings and staff downgradings were announced earlier this week.

The new chairman also announced that the first major conference to discuss the "gender gap" and the GOP will be held May 20 in Indianapolis. The meeting is focused on helping Republicans overcome a persistent Democratic advantage among women in polls and recent elections.

Fahrenkopf said that it was a mistake to say that President Reagan "has trouble with women." The problem, he said, "is concentrated among those between 21 and 40, working women and single heads of families." By identifying the specific "demographic characteristics," he said, Republicans can take necessary steps to overcome the problem.