WEST HOLLYWOOD — Grace VanderWaal is used to performing a single song, with her ukulele, before a huge crowd. It's what she did plenty of times last year before winning the grand prize on America's Got Talent.

But performing a 75-minute set, often uke-free? That's a new challenge the 13-year-old singer/songwriter faces on her first tour, which showcases her debut full-length album of the same name, Just The Beginning.

"You know, when it’s like winter going into spring, when you don’t need your jacket anymore? And you become so used to putting your hands in your pockets?" she says, chatting backstage at The Troubadour before the first of 13 concert stops. "I don’t know what to do (with my hands onstage). It’s kind of like that where you feel so vulnerable and weird."

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What VanderWaal does wind up doing with her digits is flail them as she jumps up and down, extend them out to the crowd as she sings, shake and tap a tambourine (a new addition purchased right before the show) and, of course, play ukulele, her "safe zone."

But this isn't the green AGT VanderWaal. This is a mature recording artist who goes for high notes in So Much More Than This (a song that's "so hard to sing live"). It's a singer who invites fans to sing along for the now-classic Clay. It's someone jumps without abandon during City Song. And a performer who talks about the meaning behind Talk Good (a speech she practices, because "I’m the most awkward person on the planet"). And it's a musician who goes from playing with her three-piece band, to playing a uke solo, and singing acapella.

VanderWaal performs the AGT hits on her EP and almost all of the tracks on her new album (not Darkness Keeps Chasing Me, because "it's a bit of a Debbie Downer"), but she also adds some moody covers to the mix, including Leon Bridges' River and Billie Holiday's version of Stormy Weather ("I know all of you don't know that song, but you should listen to it," she tells young concertgoers).

The show isn't flawless: VanderWaal has a brain freeze after seeing YouTuber Jbunzie in the crowd, she admits to beginning one tune in the wrong key and she forgets a verse to one song. But she handles the mistakes with a smile, and an adorable, "Oops!" It's her first show of the tour, after all, and she's nervous.

However, you wouldn't be able to tell if you saw her right before showtime.

Before she goes onstage, she looks zen, but her "face feels like someone skinned it, put maggots in it and re-sewed it and they’re trying to get out of my face. It itches so bad," she says. "My stress shows in very, very weird ways."

Regardless, she says, "I feel so calm right now."

That is, until she's asked about how she's planning to end the show.

"I was gonna say, 'Thank you have a great night.' But should I leave them off with a lingering note? Or have them thinking, 'What did that mean?' I feel like this is dating advice. What do I leave them off on?"

She panics, quickly rethinks her set list, and keeps what she had.

She'll end on I Don't Know My Name, the song she played on the AGT audition, and she'll bring the house down.