How do I copyright personalized poems I write people as a side business?

I know I could just send in one at a time but that gets pricey & takes a while. Is there anything I can give to my customers in writing letting them know it's copyrighted? Is there a more efficient way to do this? Any suggestions would be great.

All you need to do is put this on them:
© LeeLee22 2013

Source(s):

www.copyright.gov