I recommend that you brand yourself a watermark as your signature to go on each of your photos.
Also, just like musicians and songwriters what we submit to the copyright office is in the form of 'collections'. A whole album off songs, or single book with many short stories instead of copyrighting it one at a time. Make sure you have the timestamp function on in your camera - even if you decide to crop the photo - so that at least the original as a time stamp on it. Buy a terabyte hard drive to store and back-up your photos.
And once you get enough to form a collection - here's the link to the Copyright office. http://www.copyright.gov/forms/