I found this article on hashtag.org and thought it was helpful for my twitter strategy. Maybe you'll find it useful too. http://www.hashtags.org/how-to/etiquette-how-to/how-to-ride-on-already-popular-hashtags-without-turning-people-off/
This was very helpful, and I hope more people manage to see this. One of the things I hate most about twitter are people using hashtags that have nothing to do with their tweet just so they can get more attention from people who are searching the tag.