Technically, Holly isn't a carefree spirit subsisting on cigarettes and good times—she's a runaway hillbilly child bride named Lula May who's too damaged to have a deep emotional connection with anyone but her brother.
Also, Holly charges men for "conversation" and asks for "powder room" tip money, and they follow her home begging for sex. It's not clear in the film whether or not she sleeps with any of these guys, but she finds income in much the same way a certain kind of sex worker would: She picks the richest man she can find and charms him into submission. Fact: Truman Capote, author of the novella on which the film is based, likened Holly to an "American Geisha," so take from that what you will. He also wanted Marilyn Monroe for the film because this character's charm isn't (only) her je nais se quois; it's her overt sex appeal.
There's nothing amoral about what Holly's doing, and it's clear her charm is a foil for her loneliness, insecurity, fear, and ultimately, instability. That said, it's interesting to me so many young women idolize this character. Maybe she was empowered for her time, but she's also operating almost completely as a cypher for men's desires; so can we put the mantle of early feminist role model on slightly less coquettish shoulders, please?
I'm certainly not the first to talk about this—it's a point of conversation around the web. The book and film are both all about society roles; you can frame Holly as a step backward, a master manipulator of the patriarchy, a feminist icon, or at least, an icon for feminists, and even an everywoman.
What's impossible to ignore is that Holly is also a criminal. Her steadiest source of cash is relaying coded messages from an imprisoned mobster to the outside world. Which would all be well and good, except that Holly literally has no idea that that's what she's doing. It's not that she's dumb, she's just glaringly uneducated.
