Karmin stopped by the Rolling Stone studio to give new artists tips on how to build an audience online. The duo, who broke through on the strength of clever covers of current hit songs, explain their strategy of picking tunes and engaging with YouTube viewers. They stress playing up your quirks, which in the case of singer Amy Heidemann, meant showcasing her knack for speed-rapping (and her singing chops are on full display in this interview outtake, during which they improvise a new song).

"I come from a small, conservative town in Nebraska and my grandfather was a pastor, so I was never really pushed toward rap music and I wasn't allowed to buy CDs with the parental advisory sticker," she says, noting that she picked up on hip-hop through Jay-Z's guest appearances on Mariah Carey hits. "[Rapping] came very natural for me, but I never thought I would do it publicly."

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