In short, though, the proper etiquette of sushi is simply to be polite and not eat like an animal (even though yes, we are actually animals). Simple table manners are enough to be following proper sushi etiquette, as many have pointed out. The purpose of this article, however, is to offer the reader a comprehensive guide to "traditional" sushi etiquette, much of which may be outdated in these modern times, or culturally not necessary in Western countries. Keep in mind that while sushi actually originated in China as merely a method of storing fish for later consumption, the art and excitement of what we now call sushi came from centuries of cultural evolution in Japan. What may seem odd to Westerners may not seem odd at all to someone from Japan as our customs are different. Also, what may have made sense 200 years ago, may not have the same meaning today.
Please feel free to read the article on SushiFAQ.com but do keep in mind that this is not meant to be "how you better eat sushi the next time you go out to a restaurant." It is merely an interesting article that some may find of interest that explains some of the traditions and rules of etiquette that have been part of the ritual of sushi over the centuries in a world far remove from ours, and even removed from modern Japan.
For those of you interested in making sushi at home, I would recommend checking out Sushinut.com for all the sushi grade fish you could ever want.