Sometimes, I'll have a musician work their way up the hard way. Like they'll start off singing and performing in bars and lounges, then sell their music without the help of a label. If acting's in the cards, they'll do stuff that focuses on Charisma or instrument skills.
For your sim specifically, she can probably move into music as a side thing, like many actresses. Or she can focus on charity work. Or she can get into some scandals, like having an affair with another celebrity, having a baby out of wedlock, etc. I don't know what's right for your sim, personally though. Can you tell me more about her?