Alter your pitches. Demi knows how to belt it out when she needs to. In an interview with MTV, Jocelyn Vena quotes where Demi herself claimed that she can "sing really loud on a rock song." Her rendition of the US National Anthem is another prime example. Additionally, Demi knows how to sound more conversational in her songs. Sometimes, she even sounds like she is whispering. If you want to sing like Demi Lovato, then your voice needs to have this range. Practice both ends of this range separately, then practice altering them from one second to the other. In her song "Don't Forget," Demi goes from a low to super high and back to low pitch.
Reinvent yourself constantly as a singer. Even though Demi is a die-hard rock fan, she's open to changing it up. If you want to sound like Demi Lovato, you can't just sing one genre. Jocelyn Vena's MTV interview captured where Demi Lovato expresses, "I'm now just taking that next step and learning how to make my music more radio-friendly but also stay very artistic, and for me that's R&B." Demi then goes on to say, "I can put my vocal stylings on songs that are R&B, and it showcases my vocals more than just singing really loud on a rock song."
Sing with passion. Demi Lovato is well-known and loved by her fans because of her ability to transmit passion. For Demi, writing her own music and singing about her own feelings and experiences helps translate her passion. If she wasn't invested in the songs, the audience wouldn't feel anything. She wouldn't tweet about writing her songs on Twitter if it wasn't important to her.
Look for artists to collaborate with. Apart from touring with the Jonas Brothers, Demi is also looking to branch out. According to Jocelyn Vena, Demi "would love for Drake to be on the album."
Learn to sing in Spanish. Demi taps into her Latin roots by singing in Spanish. Look to her songs like "Lo que soy."