I've found that it's helpful not only to know about something, but to know how to do something. I work at an aquarium researching, developing and writing for our exhibit program. My background is in zoology and marine biology, but what got me the job was that I know how to write (although that may not be entirely clear from this piece of writing). If you can combine your interest with a useful skill, there will be many more opportunities for you to get in the door. Good luck!