How can I improve my handwriting for free? I'm very open to ideas!?

Whenever I write an essay in school, I seem to vary my handwriting. I'm always trying to find a handwriting that I'm OK with. My natural handwriting is legible, but barely. Does anyone know of any websites that give you printable practice sheets for free? And I'm not talking about the average alphabet that you learn in kindergarten, but I want something that is recognizable, something that is unique, and also mature. I'm a 13 year old girl and I notice alot of girls writing in bubbly girly letters, but I want something that I won't be ashamed of when I'm an adult. Please help! It's driving me crazy! It doesn't matter whether it's print or cursive.