Although she's been singing for half her life, 22-year-old California native Colbie Caillat had a hard time mustering up the courage to sing before a live audience. A few years ago she even opted to take an acting class to help allay her stage fright, but that didn't pan out too well.

"I didn't overcome my fear and I quit," the singer-songwriter says from a Toronto hotel. "It's gotten better. I'm not as nervous for radio now and my own shows. I get a little nervous in the beginning but halfway through I'm good to go. But TV performances are still getting to me for sure."

After getting literally millions of hits on her MySpace page for her breezy yet polished brand of "pop-R&B-folk," Caillat released her debut album Coco earlier this year. The album recently went platinum in the U.S. and has been one of the best-selling albums on iTunes in 2007.

Yet Caillat says she hasn't had the time to realize the success she's currently having.

"It hasn't completely sunk in yet," she says with a smile. "I still try to sit down with myself and explain when the album just went platinum. I was like, 'Okay, that's a million records.' I'm still trying to figure that out in my head."

Coco features a few surefire singles including Oxygen, One Fine Wire (written after the acting-class disappearance) and the aptly titled Bubbly, a song recalling the likes of Norah Jones.

"I was sitting at home bored in my room and my friend had tuned my guitar to a different tuning," Caillat says regarding Bubbly. "At that point, I didn't know how to tune it back to the normal tuning. So I had to figure out what chords to play because they're all different, so I started playing these three chords, which are the Bubbly chords. Then I started singing a melody and the lyrics came out."

While debut albums can often be a make-or-break affair, Caillat had one ace up her sleeve in her father Ken Caillat, who was executive producer. The elder Caillat produced classic rock albums such as Fleetwood Mac's Rumours and Tusk.

"There was no head-butting," she says. "There were some father-daughter things like, 'No dad, I don't want to redo that vocal.' But he was great and I loved it because I always wanted him to produce my albums. My dad brought ideas from the '70s, certain styles of how they recorded vocals or what instruments to add."

Caillat also says she didn't change much from the MySpace demos to the final recordings on Coco, including keeping the opening question she asked producer Mikal Blue, "Will you count me in?", before performing Bubbly.

"Mikal played the guitar and he played it at a little different tempo," Caillat says. "And I was all confused so I said, 'I don't understand. Will you count me in?' He said, 'That was so cute! Let's keep that just for the demo.' Then I put it on MySpace and asked people what they thought of the song, and it stuck."

After wrapping up a North American tour, Caillat and her band are heading over to Europe for some promotional work before a string of U.S. shows next month. She also plans on touring Japan next spring before hitting other regions.

But while success means acclaim and fame, her parents have mixed feelings on their daughter's newfound stardom.

"They were a little bit hesitant and now they're really bummed because I'm never home and I was home every day before," she says. "They're worried about security. They're like, 'We don't want anybody knowing who you are! You have to tint your windows! Always have someone with you!'

"But, at the same time, they're so supportive and so happy about everything that is going on for me right now."

Hannah Montana-mania tough to match

While the current frenzy surrounding Colbie Caillat isn't on the hysterical level of say Miley Cyrus (aka Hannah Montana), she has certainly received a lot of media coverage. But Caillat says she gets most of the information second-hand.

"I get told a lot but there's never a time where I can say, 'I'm going to go to the store and buy Billboard and see where it's at," she says of Coco's chart position. "But I always go on iTunes everyday or every two days and say, 'Am I still up there? Oh, okay good.' "

Caillat, who is also releasing a new non-album song entitled Mistletoe in late November on iTunes, also says she rarely gets to see any of her own taped performances or press.

"Sometimes I get (reviews) e-mailed or sometimes somebody will bring me a copy and I read it, but I don't get to see taped things," she says. "That's why it's all not really real to me because I don't get to see any of it."

At least the one thing she is aware of first-hand is how well her shows have gone. Caillat says that she's been getting a lot of positive feedback since her earlier treks this summer.

"It's been a growing process because it's my first tour," she says. "Everyone who saw me in June and then see me now say, 'Wow you've grown so much.' I would just stand there all nervous."