Not by shaming or prosecuting users, for starters
How Do You Stop Racism on Twitter? | New Republic
In America, where free speech protections are nearly absolute, we have a different approach to noxious tweets: vigilante justice. In recent months, a number of media outlets have rounded up 140-character gripes from people dismayed over the reelection of a black president, or furious that a black hockey player scored a game-winning goal, or eager to share how the Red Dawn remake really makes them feel about Asians. The blog Jezebel even pursued some of the culprits, publishing whatever biographical details it could find online.