His advisers want him to project optimism about America and his policies while also showing some heat and energy in the right moments to challenge Mrs. Clinton.

Mr. Trump can get bored with both debate preparations and debates themselves. His advisers have been reinforcing the importance of listening and focusing on every word Mrs. Clinton says and looking for ways to counterattack.

He may not like debate preparations, but he is very competitive and wants to vanquish Mrs. Clinton on Monday night. His team has been emphasizing the best ways to win: Do not pick stupid fights with her or with the moderator; explain yourself rather than get defensive; and deliver the answers you want rather than worrying about directly answering the question.
Mock Debates

CLINTON is expected to do at least one timed mock debate this weekend.

Philippe Reines, a longtime aide to Mrs. Clinton and a close observer of her personal and political vulnerabilities, is playing Mr. Trump in her mock debate sessions.

Mrs. Clinton is mindful of the importance of “podium behavior,” as debate coaches call it. She sometimes takes notes while an opponent is speaking; she also looks directly at her opponent at times, which projects confidence. Her aim is to look steady and attentive when Mr. Trump is speaking, and to avoid visibly or audibly reacting to him too much.

TRUMP He prefers not to do a full-length mock debate, and has no set person playing Mrs. Clinton.

He is not using a lectern for mock debate drills, despite suggestions from some on his coaching team that simulating a one-on-one debate is good practice after the primary debates that featured several rivals.

Some Trump advisers are concerned that he underestimates the difficulty of standing still, talking pointedly and listening sharply for 90 minutes. In the primary debates he often receded into the background, and only jumped into the debate forcefully when he was attacked. Some advisers worry that if Mrs. Clinton surprises him, he will be caught flat-footed.

Strengths

CLINTON Dutiful student, quick to absorb information. She limited her campaign schedule after Labor Day to pore over briefing books. Up to speed on all her briefing materials.

Good self-editing skills. Mrs. Clinton grasps that answers need to be trimmed down to two minutes (and rebuttals should be even tighter) and will keep working to tighten her answers in coming days. Responds well to timers and stopwatches but also has an instinctual sense of time running out.

Aware that preparations are a relief valve. She vents frustrations during preparation sessions, joking and being sarcastic in ways she never would before a national audience.

TRUMP Unpredictable. Whether in politics or business, he takes pride in sizing up opponents based on their language, posture, eye contact, and particularly the needs and goals that his adversaries have at that moment. He will hold back, lunge forward, or stay cagey at varying points in hopes of knocking his opponent off balance.

Studying her strengths and his faults. Mr. Trump has reviewed tapes of Mrs. Clinton’s old debates as well as compilations of his own worst moments during the primary face-offs.

Self-confident. He has said repeatedly that he can handle Mrs. Clinton on stage.
Vulnerabilities

CLINTON Can appear stiff and irritable under pressure.

Sometimes packs too many facts into answers.

Tendency to get defensive about questions involving her honesty and trustworthiness. She has delivered multiple answers explaining her use of a private email server as secretary of state; she is practicing one clear, crisp answer for the debate.

Hard to predict how she will respond if relentlessly attacked on character issues like her ethics, honesty, and relationships with wealthy donors, or on her husband’s character (such as his past infidelities).

TRUMP Can be insulting and demeaning to his opponent, the debate moderator, and voters at large, which can be off-putting.

Tendency to lie on some issues (like his challenge to President Obama’s citizenship) or use incorrect information or advance conspiracy theories — all of which opens him to counterattack from Mrs. Clinton or rebukes from the moderator. Advisers are urging him to focus on big-picture themes rather than risk mangling facts. If Mrs. Clinton says he is lying, his advisers want him to focus on her trustworthiness and issues like her State Department email and accusations of favors for donors.

Lacks a range of perspectives from women as he prepares to face the first-ever female general election candidate. The only woman consistently in Trump debate preps is Kellyanne Conway, his campaign manager. While she is a savvy and strategic debate coach, Mr. Trump may be underestimating the task of taking on a woman on a big stage.
Debate Team

CLINTON Former President Bill Clinton has been attending more preparation sessions lately.

Other regulars include Ron Klain, a veteran presidential debate coach; Karen Dunn, a Washington lawyer; Joel Benenson, the campaign’s senior strategist; Mandy Grunwald and Jim Margolis, campaign media advisers; Robert Barnett, a lawyer and friend; John D. Podesta, the campaign’s chairman; and Jennifer Palmieri, the campaign’s communications director.

TRUMP Stephen K. Bannon, the campaign’s chief executive; Ms. Conway; former Mayor Rudolph W. Giuliani of New York; Gov. Chris Christie of New Jersey; Stephen Miller, a policy adviser; Jason Miller, a communications adviser; Lt. Gen. Michael T. Flynn, a retired Army officer; and Jared Kushner, Mr. Trump’s son-in-law.

The former Fox News executive Roger Ailes has not been at the last two debate sessions, but he sends memos and speaks to Mr. Trump.

Practice Setting

CLINTON Mostly in New York.

TRUMP Initially at his weekend home in Bedminster, N.J., but moved to Trump Tower in Manhattan after distractions kept popping up in Bedminster.

Source: Patrick Healy, Amy Chozick and Maggie Haberman, nytimes.com