ManageFlitter is a way to tidy up your following list easily. The site is free, and easy to use – you just log in with your Twitter account.
Once you’ve logged in, you can select the accounts that aren’t following you back, that aren’t active, or don’t have a profile image (making it more likely they’re unused or spambots). Select them, and click “Unfollow [number] later” then when you’re ready to go, click “Manually Process”
You’ll need to click each “Unfollow” button yourself but it’s pretty quick to do – there’s even an entertainment mode so you can watch a YouTube video while you do it!
Each basic account starts out with 100 unfollows a day, but it’s easy to up your limits. Follow their account for a bonus 200 unfollows, send a tweet praising them for another 200, and subscribe to their newsletter for 300 unfollows. You can also invite friends to join in and can earn up to 1200 unfollows that way.
If you did the mass follow thing when you joined Twitter, but now find it a bit overwhelming, this is a really helpful tool!