Randomly hates me, how to get in someones good books again?

Well I do first aid and I'm 14 years old, I'm a bright, bubbly outgoing girl, maybe a little outspoken, anyway -- one of the adults at my division doesn't seem to like me at all. How can I make her changer her opinion of me? Do I act quiet and kind or maybe just watch what I say? I can't recall anything I have done, and she likes all the other cadets except me, she doesn't add me on Facebook but she adds all the other kids in my division! Thanks.