1. They don't need to know everything at once.
2. Not everybody is beautiful.
3. When describing a whole different world, make sure you've actually written it all down systematically before so you don't get confused.
4. Contrary to popular belief, being able to count is very important for a writer. A character who has her first child at age 21 must not turn out to be 35 if you add up all the dates.
5. Just because nobody will notice the secret messages in your writing, doesn't mean you shouldn't add them.
6. Do not make every story autobiographic.
7. Fanfics are good for practice, but are never to be considered as serious work.
8. Your main characters do not have to be perfect in every way. When in doubt, re-read The Hunchback of Notre Dame.
9. Write for at least 10 minutes each day. Jot down new ideas and try to start as many new stories as possible. You will always have something to work on.
10. Filter unneccessary characters, no matter how awesome they are.