Frederic Gonzalo said
1 year, 4 months ago: @joanmuschampfagnani Whatever answer I was about to give, @rich-brooks stole my thunder! 
Jokes aside, I don’t get dozens of new followers per day, as he does, but I certainly can’t take the time to acknowledge each and every one of them. What I do, however, is have a quick look at each bio and, if interesting, I will take a look at recent tweets posted. If there is a common interest or shared topics, I will usually follow back. That’s the best form of acknowledgment I know. (On Twitter, at least)