Growing your follower count can be tricky. And once you figure out your own "secret sauce" and start gaining traction, you may find yourself up against Twitter's 2k killer.
Well - when your follower count reaches two thousand, Twitter looks at your "follower to following" ratio and prevents you from following any more people until you've gained more followers. Don't believe me? Take a peek around the Twitters and you'll see LOTS of folks stuck, stagnant in 2k Twitter hell.