My 7.5yo son still isn't that good at writing. It's physically hard for him to write. His writing IS legible, though, mostly due to the fact that he was forced to practice writing long before he was really ready. Did I mention that he HATES writing, even though he's capable of it?
Her writing should get better over time, due to a few factors. One is simply that her hands will mature. Second is that she'll get more practice as time goes on.
I would gently encourage writing in fun ways. Can she play waitress and write down the orders? Play "eye doctor" and draw up an eye chart? Write notes to her and encourage her to write notes back?
There are also more structured games and puzzles that involve writing. I'd introduce some of these (madlibs, word finds, crossword puzzles, suduku, etc) but I wouldn't force the issue. Even coloring books (when kids are trying to color inside the lines) encourage the hands to form the kinds of connections needed for writing. When she's developmentally ready, she'll find those things fun. If she shies away from them, then you know she's not quite ready yet.