Bill Clinton’s hearing has faded. With his head of white hair and frail frame, he looks older than his 68 years – "truly grandfatherly," as one friend said. He often jokes about what would happen if he were to "drop dead."

But even if his step has slowed, Bill Clinton is hungering once again to play a central role in his wife’s presidential campaign. And Hillary Rodham Clinton’s advisers are once again grappling with how to deploy Bill Clinton, a strategic imperative that was executed so poorly in 2008 that it resulted in some of the worst moments of her campaign.

In that race, the former president was at times a frustrated and unpredictable presence, operating on his own, calling up some of his wife’s aides to second-guess strategy and shifting the news media’s focus from her to him with stray remarks, such as when he set off African-American anger by diminishing Barack Obama’s success in South Carolina.

This time, advisers and political associates say both Clintons understand how critical it is to harness both the rare gifts and rash impulses of a former president on behalf of a potential one. Whether this will work is a great unknown of the 2016 race: If Bill Clinton veers far off script with just one stunner of a comment, the campaign could stumble.

Some plans are already forming, the couple’s advisers say. Hillary Clinton, who is expected to announce her candidacy next month, will shoulder most retail campaign events without him this year, even though Bill Clinton is more of a natural at them. Putting her in close-in settings with voters at house parties and diners will allow her to avoid Bill Clinton’s shadow, while underscoring the message that she is taking no voter for granted.

Bill Clinton has talked to friends about courting a demographic group that he sees as crucial in the next election – Latinos – as well as reaching out to other key constituencies like African-Americans, to elected officials and to high-dollar donors.

In hopes of collaborating with Bill Clinton better than in 2008 – if not controlling him outright – advisers to Hillary Clinton are involving him more closely in early campaign planning, and they are discussing whether to deploy a senior aide to travel with him to keep him focused on his wife’s central message. The strategy would channel his myriad political talents, such as synthesizing polling data with ground operations in important states like Florida, which he is preoccupied with winning in 2016. Bill Clinton views both former Gov. Jeb Bush and Sen. Marco Rubio as particular threats, given their strength in that state – their mutual home base – and their ability to reach out (in fluent Spanish) to Hispanic voters.

They are also making sure he has clear channels to share ideas and concerns with important players besides Hillary Clinton; the likely campaign chairman, John D. Podesta, a former chief of staff in the Clinton administration, and the campaign manager Robby Mook will be taking his calls.

But the terrain is tricky: Bill Clinton is never as enraged or unpredictable as when his wife comes under attack. He will also remain focused on the Clinton Foundation, which has come under criticism for its fundraising practices. (While Hillary Clinton is likely to be campaigning in the next several months, Bill Clinton will have a packed schedule of foundation-related events, including a big trip to Africa with supporters of his charity.) He runs the risk of reinforcing a Republican argument that the Clintons are America’s baby boomer past and do not represent a generational change in leadership. And he remains a wild card: What part would he play if he returned to the White House as first gentleman?

"I can’t think of anything tougher than being him in Secretary Clinton’s presidential campaign, because no matter what he does, people will take exception to it," said Jerry Crawford, who was Hillary Clinton’s Midwest co-chairman in 2008 and Bill Clinton’s Iowa state director in 1992 and 1996.

"But at the same time, who would you rather have as a messenger and a strategist?" added Crawford, who speaks to the Clintons regularly. "And he learned a lot in 2008. First and foremost, he found out the last time how hard it is to be objective when it’s your spouse running."

In the years since the bruising 2008 primary campaign, Clinton has regained his image as a Democratic stalwart, particularly by being a devoted surrogate to Obama and delivering a much-praised speech at the party’s convention in 2012. Fifty-six percent of Americans have a positive opinion of Clinton, making him more popular than both Obama and Hillary Clinton, according to a Wall Street Journal-NBC News poll released this month. Clinton’s state of mind these days, according to people who are associated with him, can be summed up as Zen and jolly.

Clinton has also brushed up on how modern campaigns are waged. "The Victory Lab: The Secret Science of Winning Campaigns," a 2012 book by Sasha Issenberg about how data and analytics have upended presidential campaigns, caught Clinton’s eye in an article he read.

Still, Clinton often cannot help being himself. And nothing animates him more than offering his views on political strategy, sometimes with surprising company.

In September 2012, when Mitt Romney, the Republican presidential nominee, spoke at the annual Clinton Global Initiative gathering in New York, Clinton gave him advice backstage about how to appear in command when facing off against Obama in their coming debates.

"President Clinton still has one of the most politically strategic and tactical minds in America, and you want that on your side," said Jay S. Jacobs, a prominent New York Democrat who speaks periodically with both Clintons. "He watches candidates. He knows their strengths and weaknesses. And he’s always interested in talking about the Electoral College map, down to the congressional district."

That tendency to analyze out loud turned into a liability when he saw his wife’s shot at the presidency in 2008 begin to slip away. After it became apparent Obama won the South Carolina primary that year, Bill Clinton memorably compared the victory to the Rev. Jesse L. Jackson’s two victories in the state, seeming to marginalize the achievement. He also called Obama’s anti-war position "the biggest fairy tale I’ve ever seen," a comment that enraged some African-Americans who interpreted the comment to mean that Obama’s candidacy was a fantasy.

"He had some bumps in the road down here," said state Sen. John W. Matthews Jr., who was a co-chairman of Hillary Clinton’s South Carolina operation. "I don’t think those bumps were all self-inflicted, but the campaign would be smart to plan and invest more wisely next time."

This past fall, the former president proved an energetic messenger for his party, campaigning for Democratic candidates at more than 70 events. But his outsize personality can at times eclipse his less gregarious wife.

In September, Hillary Clinton took the critical step of returning to Iowa for the first time since she lost in 2008, to reintroduce herself to the state at the annual steak fry hosted by Sen. Tom Harkin, a must stop for Democratic presidential hopefuls.

Wearing a red checkered button-down shirt that resembled a picnic blanket, Bill Clinton held a 15-minute impromptu powwow with reporters and delivered a 30-minute speech about topics as varied as development in Haiti and the conservative megadonors Charles G. and David H. Koch.

"We saved the best for last, didn’t we, folks?" Harkin said when he introduced Bill Clinton, who spoke after Hillary Clinton. A Yahoo News headline read: "Hillary Clinton Returns to Iowa, and Bill Clinton Almost Steals the Show."

On an organizational level, Hillary Clinton’s advisers are taking steps to avoid 2008-style dysfunction when Bill Clinton’s team functioned apart from her campaign. The two operations were so independent that questions arose at times about whether some aides to the Clintons were more loyal to one or the other and whose marching orders they were following.

This time, the staffs of Bill and Hillary Clinton are more intertwined. Podesta, the likely campaign chairman, has known the former president since the McGovern campaign of 1972. Bill Clinton’s chief of staff, Tina Flournoy, is in regular contact with the expected campaign team and commands significant respect from Hillary Clinton’s aides.

One idea being floated is that a white board be set up at the Clinton campaign headquarters in Brooklyn for strategizing with a "W.J.C." category for Bill Clinton’s suggestions.

Making sure Bill Clinton has his own campaign aides is a priority: As he has aged and retained a demanding schedule, he has become more dependent on a staff. Clinton, who has lost more than 20 pounds since 2008, sends an aide to buy his dress shirts at Bergdorf Goodman, and when he steps out of his chauffeured SUV, he sometimes spreads his arms awaiting an aide to put his jacket on each arm.

Perhaps the person best positioned to keep Clinton from overdoing it is his daughter, Chelsea, who in recent years has taken on a leadership position at the Clinton Foundation. He has said that if his wife wins the White House, he will maintain the family’s home in Chappaqua, New York, and continue to lead the philanthropy. "I hope I’ll get permission to keep this foundation going," Clinton recently told Queen Latifah on her talk show.

The foundation, which has received millions of dollars in donations from foreign governments, has come under criticism for potential conflicts of interest while Hillary Clinton served as secretary of state, concerns that would most likely persist should she win the White House. A spokesman for the Clinton Foundation, Craig Minassian, said "Should Secretary Clinton decide to run for office, we will continue to ensure the foundation’s policies and practices regarding support from international partners are appropriate, just as we did when she served as secretary of state."

This month in Miami, Bill Clinton showed he could follow orders at a volunteer day organized by a Clinton Foundation initiative in the city’s impoverished Liberty City neighborhood. After Chelsea Clinton delivered remarks, her father, in a baby blue "Day of Action" T-shirt, bluejeans and his favorite red sneakers, took the microphone. "My main job is just to thank people," the typically verbose Clinton said in remarks that lasted a few minutes. He dutifully thanked the Miami-Dade police and the members of the Miami Dolphins who were in attendance.

Later that morning, Clinton walked through Liberty City to check out a community vegetable garden near a public-housing project. A reporter tried to get Clinton to comment on news reports of his wife’s use of a private email account while she served as secretary of state.

"I have an opinion, but I have a bias," Clinton said. When asked what his opinion was, he paused. "That I shouldn’t be making news on this."

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