This year, Sophie Westenra has just one resolution: to give acting her very best shot.
The 19-year-old's Grey Lynn townhouse, which she is renting from big sister Hayley, 22, is still at the moving-in stage.
Westenra is sleeping on an airbed and has propped the TV up on a cardboard box.
But she looks immaculate in a sundress and sandals, cool and pale on a day that makes the rest of Auckland sweat and flush.
Acting, for Westenra, is no pipe-dream. In the last couple of months this slender, composed teenager has put her university studies on ice, moved out of her family home in Christchurch, and got herself an agent.
Westenra is already cultivating her singer's voice into an American drawl and has taken acting workshops taught by actress Miranda Harcourt, who is deeply impressed by the girl formerly known as Hayley's little sister.
"There's a million pretty girls in the world, and she's very pretty, but you know, so what?," says Harcourt.
"But she's got a really amazing quality, that comes through on camera more than it does when you're just chatting to her ... it seems like she's thinking of something very interesting and intriguing. You really want to know what she's thinking."
After the workshop, Harcourt emailed Westenra's agent, Karen Kay, to tell her the teenager had "something special".
Westenra, who until now always chose a sensible path, is just revelling in the fact that her acting future is unknown - and that it has nothing to do with Hayley, who had sung herself to fame by the time her younger sister was 12.
Westenra's voice is very like Hayley's, and she has fans of her own who are clamouring for an album.
But she has stuck to singing at the odd Christmas in the Park concert and contributing backing vocals to some of Hayley's albums.
"I saw what happened to my sister," Westenra says.
"It's quite a stressful job, Hayley's job, very high-pressure, full-on, and high profile.
"I thought, 'Oh, I don't want to get into any of that', and I was going to do medicine."
So at Burnside High in Christchurch, Westenra focused on the sciences, until Year 12 when she realised that if she did medicine, she wouldn't have time for any music.
She marched into the school office and switched to arts, and went on to study law and music at the University of Canterbury.
In her first year she topped criminology and won a music prize, but put her studies on hold after an epiphany.
"An actress was in the audience and she came up to me afterwards and congratulated me on my performance, and said she loved my singing and everything, but I was a natural actress," says Westenra.
The actress' name has slipped Westenra's mind but the comment, she says, gave her the confidence to take the plunge.
"I'd always wanted to do acting but I didn't see it as a viable option, and also you wonder if you really can do it."
Her first role was in Annie, aged four, and she continued to act in shows until high school.
Stage fright during singing performances bothered her, thanks to the inevitable comparisons with Hayley. "I think I'm just now getting the confidence to do exactly what I want ... Now I want to give acting a go, that's my own area, something completely different, you know?
"People can't compare me to Hayley at all."
Acting, Westenra says, lets her "immerse myself in someone else's world". That's attractive, to a girl who learned at 14 that her family could never go on another camping trip, because Hayley got hassled so much.
The Westenras - mum Jill, dad Gerald, Hayley and youngest child Isaac, an engineering student - are on a long family holiday now, sunning themselves at a house Westenra will only reveal is "up in the top of the South Island".
They have plans to meet Ronan Keating for lunch this year, and to meet Prince William during his New Zealand tour.
Meanwhile, the gossip magazines are whispering about Hayley's mystery boyfriend, who is with the family for Christmas. Westenra says she has nothing to hide: she is single, with no murky past.
"My sister's been fine because there have been no scandals to dig up ... That's the kind of person she is, and that's the kind of person I am, really."
So will Westenra's gamble - her decision to leave home, and university, to chase acting work - pay off?
Harcourt says: "She's got a lovely talent, and fingers crossed ... But she's never going to find out unless she does it and I really admire that she's got the balls and also the very good planning skills at her age, to go, 'Well, I'll give it a go and see what happens'."