* The cover-up was essentially directed by the president, overseen by the White House Chief of Staff, and at the operational level run by the White House Counsel.
* A false story was concocted.
* Both at the White House and at the campaign committee, everyone involved destroyed evidence.
* Low-level people arrested for the initial break-in were paid off to stay quiet; they were also promised pardons (or at least pardons were hinted at). Among those directly involved in directing and raising funds specifically to be used for hush money were the White House Chief of Staff and, probably, the President of the United States.
* Others lied to the FBI and to a grand jury; the White House Counsel prepped them for the grand jury so they would stick to the cover story.
* The White House counsel also arranged to receive regular briefings from Department of Justice prosecutors, including FBI interview reports, so that the cover-up could stay one step ahead of the law
* When that arrangement became public and collapsed, the president himself began receiving regular briefings from the Department of Justice, about their prosecution strategy, including grand jury testimony, which he then shared with targets of the prosecutions. That arrangement only stopped when the president pushed too hard for information, and really only stopped for good when a special prosecutor, beyond the reach of the president, was appointed.
* The President of the United States had his chief domestic adviser, the second-ranking White House staffer, order the CIA to tell the FBI to stop the investigation based on a false claim about,
* Part of the reason for the cover-up was to protect illegal White House operations (Watergate itself was basically a campaign operation, although with plenty of blurry lines). The president specifically ordered the head of the the Department of Justice Criminal Division not to look into an illegal White House activity based on a false claim of national security.
* And that's just the internal story -- the real cover-up. To the public, the Nixon Administration falsely claimed that the White House was not involved in the original crime, falsely claimed that his White House Counsel had carried out an investigation and written a report clearing the White House, and denied several -- maybe dozens -- of specific, true, press reports.
By the way, I'll stick with what I always say about this: it's the crime, not the cover-up, that gets people in trouble. The reason for the Watergate cover-up was that specific crimes had been committed, crimes which could have (had they been confessed to in June 1972) sent much of the senior White House staff, much of the campaign organization, and perhaps the President of the United States straight to prison.
And, for those who are not following my Watergate updates, the above does not include the cover-up of the cover-up; once the initial cover-up collapsed in spring 1973, the president then initiated a new cover story which falsely claimed that he himself had not been involved in the cover-up at all. Because, again, the alternative was admitting the truth, which was worse.