Search the site for hashtags, and from Analytics Pages, like #infosec, study the analytics on engagement to make prudent decisions on those that are most likely to get your posts, updates and Tweets coming up in searches and get your links clicked.
Explore hashtags suggested for your searched hashtag in the spherical tree to find relevant hashtags with better engagement:
Compare hashtag analytics and save the hashtags you will use again and again in TagSets (in the RiteTag site as well as in RiteForge extension and app and the RiteBoost Bulk Creator dashboard, too)
Then, use the bookmark icon beside the clicked-on hashtag to bookmark it to the bottom of the page. You can then compare analytics on a few and when you've made final decisions, save them as a TagSet. TagSets are accessible from the browser extension in all integrated sites and a large TagSet is a quick copy-paste solution for Instagram as well.
Pro tip: view the Unique Tweets/hour as your competition, the Exposure and Retweets/hour as your wins. Choose hashtags that have high numbers on these two vs. Uniques for best results.