Make it obvious what action (and benefit) a visitor can expect from a button click. This is not to say that a button’s call-to-action should be wordy or ingenious.

Facebook has added three new call-to-action buttons that have been integrated with Messenger. Whenever someone clicks on one of these buttons, it will create a new Messenger thread.

“Over the course of a three-week test, the Sign Up call-to-action button delivered a 2.5x higher conversion rate versus other comparable social placements aimed to drive new user acquisition ...