"You've got to be careful about what you put out there and what you really want people to know," she told MTV. "And keep some for yourself! Keep some secrets so you can write a book later on."
Melissa Joan Hart would know, as she just released a tell-all book of her own called Melissa Explains It All. But Cyrus appears to have no qualms about revealing her true self in public. Last weekend, the singer made headlines for smoking a joint onstage at the MTV Europe Music Awards. But while some have criticized Cyrus for her actions, Hart argued that it's too early to judge the star.
"People like Miley Cyrus, she's incredibly talented, and she got a lot of notoriety for, you know, acting like a young girl onstage and I think she'll be alright," she said. "You can't judge her on that, you have to wait another five to ten years to see where she goes. When you're a teenager or a young adult, you think that everything you have to say is the most important thing ever and the funniest thing ever or the coolest thing ever and you share it all."
Melissa Joan Hart also sympathized with how difficult it is for young stars in Hollywood today. The former Clarissa Explains It All actress noted how the Internet and social media have made it nearly impossible to maintain privacy.
"The business has changed from when I was young," the 37-year-old said. "There weren't things like social media there wasn't the Internet, there wasn't TMZ and there weren't all these outlets and they need content to fill so they're digging more into people's personal lives and following you around and looking at everything from 'Was your underwear sticking out of your jeans?' to 'Did you take the trash out?'"
Watch Melissa Joan Hart's MTV interview below.
Also this week, Melissa Joan Hart dished to Access Hollywood about her hookups with some of Hollywood's hottest actors. In particular, she spoke about making out with a young Ryan Reynolds after meeting him on the set of the Sabrina The Teenage Witch movie in 1996.
"He gave me this beautiful watch and ran out of my dressing room," she said. "I chased him down and in the headlight of his car, I stopped him ... and I just grabbed him and kissed him. We just made out all night ... Ryan has grown up nicely."
But not all of her kisses were this romantic. In fact, Hart revealed she had a bad experience smooching James Van Der Beek on-screen for a Clarissa episode.
"It was really awkward and really uncomfortable," she said. "Just weird."