Twitter is a major tool for any artist or band, providing major engagement and promotion capabilities. That said, sometimes it's a lot more difficult to keep your followers than it is to add them.
The social media distribution service Buffer did a study to determine why users unfollow someone and they found out that the biggest reason by far is because of too many tweets within a short period of time, or bursts.
Followers don't mind a lot of tweets, but they hate when you seem to be monopolizing their Twitter feed.
Solution - Make sure that you space your tweets by using a tool like Buffer, Tweetdeck or Hootsuite.
Other reasons that are fall far behind on the annoyance scale are uninteresting topics, mundane details, and politics.
Solution - Don't post unless you have something to say, and make sure that any details are relevant to the conversation. And unless your music or brand has a political edge, stay away from politics completely as you'll likely lose at least half your audience.