"Maybe you've tried a guide before and found it spoke only about face-to-face arguments. Or maybe you're new to the online world and baffled by this chaotic new medium. This guide
is just for you! Whether you're a baby troll or an experienced flame warrior, we can teach the best way to make your online environment a safe, friendly, colorblind place. Soon the World Wide Web will be your home away from home — and like your home, it will be full of only the people you want to see."
For example, "Responding to what your opponent says should always be a last resort. To do so requires the extra effort of reading someone else's words and considering the implications of unfamiliar or uncomfortable thoughts. The discussion will go much faster if you just assume your opponent has said what you want to argue about and respond to that instead."
More suggestions here
.ETA: Quoted with permission.