“Oh, you know, sure, I loved New York, that goofy evolution museum, the 20 false alarms when I saw Osama bin Laden driving a taxi.”

It's easy to parody Sarah Palin after her disastrous appearances with the CBS anchor Katie Couric: those long pauses when it looked as though she was tracking a moose, the flapping earrings in the shape of Alaska, the holiday snaps in New York with leaders of countries she couldn't pronounce.

Tonight in the vice-presidential debate the Republican candidate has the chance to redeem herself or self-destruct. For the past three days she has been holed up in the McCain ranch in Arizona going through her cheerleader routine, having been tutored by Dr Henry Kissinger. Main Street America desperately wants a champion, but can hockey mom conceivably win the debate against the Democrat Joe Biden when she doesn't know her Sunni from her Shia?

Mrs Palin needs to be herself. Anthony Gordon Lennox, a British communications specialist who has advised her for the debate, says: “She has been showing too much fear and responding too fulsomely to questions. She can't get bogged down in economics, she has to tell people what makes her heart beat.”

The candidate who launched a million fringes has won sympathy for being a mum and having five children. But she needs to slow down to look authoritative and talk about her own experiences without sounding mawkish. Unlike most male candidates, Mrs Palin tends to use less than her allotted time and ends her answers abruptly, which is why the McCain team negotiated for less time.

The rules are different for women. Tim Bell, Margaret Thatcher's adviser, devoted his evenings to coaching the first female leader of the Conservative Party. He taught her to lower her voice and to wear her hair in a helmet but he says he couldn't achieve the same for Mrs Palin. “She doesn't have the intellectual grasp. I didn't have to spell out Margaret Thatcher's own policies to her, I just had to encourage her to use humour and the right amount of aggression. I don't think any amount of preparation could help Palin; it's going to be bloody.”

Both he and Dick Morris, President Clinton's adviser, agree that Mrs Palin's best bet is to write down ten truths she wants to tell the American public and emphasise her can-do spirit.

Tony Blair's aides disagree. They believe that the only way Mrs Palin could win is to provoke Biden into being condescending and patronising. Phil Collins, one of Mr Blair's former speechwriters, says that John Prescott kept going for years because people thought he was ordinary. “Every time Biden attacks her, he will be putting down Middle America.” Any hint of grandeur from Senator Biden will help Mrs Palin. Meanwhile she can get away with ridiculing her opponent and criticising Barack Obama as long as she isn't shrill.

Tim Allan, who worked to change “Bambi” Blair's image, says: “She is going into the debate with expectations at rock bottom, which helps. She should make a virtue of her simple, first principles approach.”

Kirsty Allsopp, the television presenter, can't face watching the debate tonight. “The thought makes me feel slightly sick. She's a real horror but there is something about her that puts you on her side. Her best bet is to sound honest. When asked why she doesn't know anything about foreign policy, she should say: 'I've got five kids and a limited budget, where on earth would I get the time or money to go on foreign jaunts?' That would make Biden pause.”

Martin Bell, who made his political reputation on being an outsider, says: “If you are going to be the political ingénue and pit one month's national experience against Biden's 36 years, you won't be expected to know everything. But she needs to pick a couple of policy areas where she really knows her stuff.” Creationism is not one, but she should talk about energy policy, work life balance and saving for a rainy day.

A new book could give Mrs Palin some clues on how to conduct herself. The Case Against Barack Obama, by David Freddoso, argues that far from being the embodiment of change, Mr Obama is a traditional machine politician with no record of reform.

The book's conclusion is that Mr Obama is not a reformer, nor a Messiah: he is just like the rest of them in Washington. Whatever Sarah Palin is, she is not a creature of the Beltway.

Mr Obama thought that he could get away with an experienced running mate because he himself offered the American people, if anything, too much change. If Mr Obama is just another political hack, then Mrs Palin could yet be the electoral game changer that the Republicans were looking for when they chose a small-town mayor who knew how to field-dress a moose. That's the impression she needs to reinforce tonight.

Like David Cameron yesterday, she should embrace her lack of experience, and proclaim, as he did, that “what matters more than experience is character and judgment and what you really believe needs to happen to make things right”.

Tips for the Barracuda

Forget the past ten days and all the facts you have been cramming; they will just confuse you.

Take on your detractors and the media for ridiculing your assertions that you know Russia because you can see it from your bedroom window.

Senator Biden has had 36 years of experience and 36 years to condescend to the electorate. His answers are dense, yours should be light. Trust your instincts; you are at your best when you talk about families and the old.

Your son is in Iraq so don't feel embarrassed about talking about the emotional consequences of war, they are just as significant as the political ones.

Deliver one detailed answer on a subject you know more about than Biden. Not gunning down wolves from planes but energy policy, which you understand.

Don't get bogged down in the $700 billion bailout, talk about Main Street America, its concerns and worries. None of the other candidates can do this without sounding insincere.

Use your own jokes, they're great. Just not the ones about polar bears.

Tease Biden and goad him. The more aggressive he sounds the better, especially if he is patronising.

A last word from Sir David Frost, who has interviewed six British prime ministers and seven US presidents. “In a debate candidates have to do just two things: make sure they don't make a mistake and remain calm and relaxed. It's easy.”

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