It seems like I've been writing since birth! I started writing poems before I got to school. I wrote the class musical in first grade — both words and music. It was about a bunch of vegetables who got together in a salad. I played the chief carrot!
I read everything aloud, novels as well as picture books. I believe the eye and ear are different listeners. So as writers, we have to please both.
Write every day. You don't have to write about anything specific, but you should exercise your writing muscle constantly.
My youngest son becomes an award-winning nature photographer, and I cannot resist writing poems to his pictures. My daughter loves to cook, though I do not. Yet together, we write a cookbook with fairy tales. And now a second.
If you give up at the first rejection or the first bad review, you will never make it in publishing.
Read something of interest every day — something of interest to you, not to your teacher or your best friend or your minister/rabbi/priest. Comics count. So does poetry. So do editorials in your school newspaper. Or a biography of a rock star. Or an instructional manual. Or the Bible.