So then, how do you find relevant and popular hashtags that people actually use? There's actually a very handy resource for that: Hashtags.org. This website tracks the currently trending hashtags on Twitter. If you find a good hashtag to chime in on, it's great material for a tweet. Stay as relevant to the audience that you are trying to create and sustain, but it's okay to stray a bit here and there to respond to a random trending hashtag. It helps you look human to other Twitter users, which is always a good thing. The last thing you want to be is a re-tweeting machine who just mechanically posts content for the sake of flooding Twitter feeds.
Hashtags.org also provides popular hashtags for different categories and even allows you to search for a certain hashtag, giving you a 24-hour trend graph for that particular hashtag. It even shows the time of day that the hashtag was most popular. The more popular it is, the more likely you'll get people to see your tweet. So much of the activity on Twitter is noise, so it's important to rise above the general chatter and look as relevant as possible.
Another great tool for researching hashtags is hashtagify.me. This hashtag tool also considers hashtags on Facebook, Google+, and Instagram, as well as Twitter. The specific thing that hashtagify.me can do is find your related hashtags to the one you are searching, as well as show you the top influencers for that hashtag, and recent content using that hashtag. There is additional usage pattern data that you can access for free just by putting in your name and email and making an account.
By finding hashtags that are both popular and relate well to the topics you are sharing, you can find entirely new audiences for your content! Just be sure to not go way overboard and stuff your tweets full of hashtags. Who wants to look at posts of nothing but hashtags? The idea is to stay relevant - the last thing you want to do is spam.