Today I read a tip on Tips for Young Writers it is very true.
"Re-write, re-write, re-write. Tear every sentence apart and analyze it. Does it flow? Is it passive or active? The best writers use an active writing voice as much as possible. So instead of saying: “She picked up the pencil,” say instead, “She grabbed the pencil.” Don’t sweat it if it seems to take a century to create something good, that’s how you learn. And with experience the writing process becomes easier. Promise."
Another good tip is to always check your work. It is a good idea to use a dictionary while you are checking it. You may also change words to make it more exiting. You can look up words your not sure about and it will help you write a good story. It will also help to read it aloud that way you can hear how it sounds.