ON JULY 20, 1973, Gordon Strachan sat beneath the glaring lights of the Senate Watergate Committee. He was the aide to Richard Nixon's chief of staff, H. R. Haldeman. Strachan was the young attorney who had recruited Donald Segretti and who had turned over the $350,000 cash to Frederick LaRue, which was used to silence the original Watergate defendants.

After reading his 15-page testimony, Strachan was asked if he had any advice for younger Americans about government service.

"Stay away," he said evenly, as the onlookers laughed. "Well it might sound - it may not be the type of advice you could look back and want to give but my advice would be to stay away."

Soon after the hearings Strachan moved to Utah where his wife was hired at the University of Utah College of Law. Today Strachan, 33, works for the Salt Lake City firm of Burman and Giaugue.

"Life is treating me very well," he said in a telephone interview last, week, sounding cheerful. In March, 1975, all criminal charges against Strachan, who had been promised immunity for his testimony, were dropped.

Strachan described the firm as "composed of 10 guys," and his work as "representing plaintiffs in antitrust cases." As for the past, he's reluctant to discuss it. He said, "I would just as soon pass any questions. I'm trying to retain my life as is, I like being out of sight."

Ronald Ziegler was 29 when he became the White House press secretary, the youngest ever. He was a confirmed team player and a man whose loyalties and shared conservatism moved him closer and closer to Nixon.

For months Ziegler had held off a frustrated press on Watergate, unflinchingly protecting his boss. Then one day, whammy, whatever truce, whatever credibility existed, was gone. On April 17, 1973, Ziegler told the White House reporters that all past Watergate statements were "inoperative."

Ziegler, who stayed with Nixon until February, 1975, is now senior vice president and management director of Syska and Hennessy, an international engineering consulting firm. It was the marketing and advertising world that had prepared him for his public job. After the White House he had wished for a journalism career that never materialized.

"I will write a book someday," said Ziegler from the firm's New York office. "But now I spend time traveling between the offices in New York and Washington. I have also been going to Europe, the Middle East and South America." His family has kept their residence in Alexandria and Ziegler is usually in Washington two days a week. "We're very happy with our lives right now," said Ziegler, who will be 38 this week.

Asked about his administration's press secretary, Jody Powell, Ziegler said any real advice he would give to Powell in private but added, "I think he's doing a good job. He seems to have a good relationship with the President and appears to have a grasp of all the dynamics."

He had read "Six Crises," especially noting the young Richard Nixon's zeal in his pursuit of Alger Hiss. Then Egil (Bud) Krogh, officially the White House liaison for the District of Columbia but also the head of the "plumbers" unit, directed the break-in to the offices of Danile Ellsberg's psychiatirst.

Later Krogh said that Nixon had not ordered the break-in and for himself, Krogh said, "The invocation of national security stopped me from asking the question 'Is this the right thing to do?'"

Now Krogh is posing that very question to the graduate students at Golden Gate University where he is teaching public administration. After he served five months of a six-month sentence for conspiracy in the Ellsberg case, Krogh went to work for Rep. Paul N. (Pete) McCloskey (R-Calif.), a friend of John Ehrlichman. At first Krogh worked as a legislative assistant in the Washington office and then switched to McCloskey's district office in Palo Alto where he worked on energy-related programs.

Next Krogh went to work for Swensen's Ice Cream, the popular manufacturer headquartered in San Francisco, where he was director of development until February, 1977.

At Golden Gate University this semester, Krogh, 37, is teaching Public Policy Analysis and the Dynamics of Administration in a Changing Society. This summer he's scheduled to teach Values and Conflict in a Changing Society. His secretary says, "The students love him and he's an excellent teacher."

Alexander Butterfield, the member of H.R. Haldeman's staff who revealed the existence of the White House tape recordings, had a hard time for a while. After he left the White House he headed the Federal Aviation Administration from March, 1973 until he was fired by President Ford in March, 1975.

Then Butterfield failed to regain his rank of retired Air Force colonel that he gave up when he became FAA administrator. One broadcast even tagged him as a CIA contact. He denied the charge and said the allegation - never proven - had done him irreparable damage.

After a long job hunt Butterfield became executive vice president of the International Air Service Co., Ltd., in Burlingame, Calif. He's been on the job since Jan. 10, 1977, his secretary said, and has a firm policy of not talking to reporters.