Antonyms for the phrase "tails away" include "pick up," "gather steam," "gain momentum," "strengthen," "intensify," and "build up." These phrases describe actions that denote an increase or improvement, as opposed to "tails away," which can signify a decrease or weakening. For example, if a project at work is starting to "tails away," one might suggest to their team that they need to "pick up the pace" or "intensify their efforts" in order to prevent the project from failing. Basically, antonyms for "tails away" are words or expressions that convey the opposite meaning of loss or decline, and instead portray growth, strength, and progress.