The "best hashtags" are going to be different for every business and every tweet. I use a Google Chrome browser extension called RiteTag Twitter Hashtags Grader to help me select hashtags that will increase the likelihood of my tweets being discovered. Because what you really want on Twitter is for people to discover you from one of your tweets and be intrigued enough to follow you.
I compose every tweet as follows: First, I add the meat of the content (text, link, photo). Then I throw in a few hashtags that I think best represent my content. A tweet containing news about the jewelry industry might use #jewelry, #trends, #fashion, #style, etc. The RiteTag extension uses a very simple color coding scheme to indicate which of my hashtags is good vs great vs overused. An overused hashtag will cause me to be lost in the shuffle of everyone else using that same hashtag. A good hashtag might get me found but the likelihood is low. A great hashtag gives me a high chance of being discovered, so I aim to use at least one great hashtag per tweet. RiteTag's color coding scheme is super easy to understand and it uses current trends to decide how to grade each hashtag.
You can learn more about RiteTag here:
https://ritetag.com.
