Middleton has had plenty of training from someone who should know; her future husband.
"It's obviously nerve-wracking because I don't know what I'm sort of... I don't know the ropes really," Kate said in the couple's first news conference as an engaged couple. "William is obviously used to it, but I'm willing to learn quickly and work hard."
And she'll have to. Editor of "Majesty" magazine, Ingrid Seward, tells CBS' "The Early Show" that, although Kate's been around William for eight years, "she doesn't really know what she's getting herself in for... none of us know what she's really getting herself in for."
Seward says Middleton will have to be on her best behavior in the coming months, and above all else, "just keep smiling."
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Middleton wasn't born for the sort or public life she'll now have. The Middleton family are commoners - albeit millionaire commoners.
They live in, what was until now, a sleepy rural village about one hour west of London.
Father Michael, a former airline pilot and mother Carol, an ex-flight attendant, now run a children's party supply firm. But for local residents, Kate Middleton was always a princess in the making.
"Well, she's beautiful in photographs, but in real life she's absolutely stunning," says Linda Tillotson, a local shopkeeper in the village of Bucklebury. "She's just got the most amazing personality. She'll make a super princess."
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As Kate was William's special guest when he graduated from the British military officer's college at Sandhurst, Britain's upper "chattering classes" had to get used to the idea that she might be the one - even if they didn't like it.
"I think Kate is soothing and comfortable to him, she's absolutely there for him," says longtime royal watcher Victoria Mather. "Her whole life to date has been, since she's met him, has been tailored around him - and to her own detriment, that she has not had a job."
What she did have was loyalty, and the prince's eye. And staying power.
Even Britain's voracious press has been unable to catch Middleton in an untoward moment.
"She hasn't once put her foot wrong, even when briefly she split up with William and there was talk of him not being convinced that she was the one," notes Camilla Tominey, royal correspondent for The Express newspaper. "She went out in the most glamorous frock she could find, before you knew it, the future king was back knocking on her door and saying he'd made a terrible mistake."
After eight years of persistence, one formerly dubbed "Waity Katie" has proven the wait was worth it -- and it's now finally over.
Katie Nicholl, the author of "William and Harry: Behind the Palace Walls," said there's a lot to this girl - don't underestimate her." Speaking to "The Early Show," Nicholl, predicted Middleton will be "a real breath of fresh for the House of Windsor."
And addressing the perception Middleton is demure, Nicholl said, "She's an awful lot of fun. She can drink William under the table!"
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