This page explains what user talk namespace templates are, and how to use them within Wikipedia. You can click on the tabs at the top of this page for detailed information about how to use these templates, as well as how they have been designed.
User talk templates are placed on users' talk pages to advise a user against actions that disrupt Wikipedia, to advise editors of common mistakes, or to place a standard boilerplate note at the top of a page. They are designed to convey a standardized message. The purpose of user warnings is to guide good-faith testers and dissuade bad-faith vandals or editors engaging in disruptive editing. You should check that the user has made harmful or disruptive edits before issuing a warning, and that they have not already been warned for the same action by another editor. The user must be given a chance to see, and react to, each warning given.
User blocks serve to prevent further disruption, or to protect Wikipedia, rather than to punish users. If a user stopped vandalizing some time ago, and their edit histories don't suggest a pattern of chronic vandalism, there's no need to warn or block them at all; a welcome template for new users might help future visits. Conversely, if a user is in the midst of an obviously bad-faith vandalism spree, there's no need for them to be warned before an administrator temporarily blocks them. You should ensure that you are familiar with the content of templates before issuing them. If the tone or content of a template isn't appropriate, don't use the template — just say it normally, because it likely would violate basic WP:CIVIL.
Quoted & rearranged from: WP:CIVIL.
Incivility – or the appearance of incivility – sometimes arises from placing (inappropriate) warning templates and unprofessionally fighting (alleged) vandalism.
Be careful with user warning templates. Be careful about issuing templated messages to editors you're currently involved in a dispute with, and exercise caution when using templated messages for newcomers (see Wikipedia:Please do not bite the newcomers). Consider using a personal message instead of, or in addition to, the templated message.
Explain yourself. Insufficient explanations for edits can be perceived as uncivil. Use good edit summaries, and use the talk page if the edit summary does not provide enough space or if a more substantive debate is likely to be needed.
Be careful with edit summaries. They are relatively short comments and thus potentially subject to misinterpretation or oversimplification. They cannot be changed after pressing "Save", and are often written in haste, particularly in stressful situations. Remember to explain your edit, especially when things are getting heated; to avoid personal comments about any editors you have disputes with; and to use the talk page to further explain your view of the situation.
Be professional. Just because we are online and unpaid does not mean we can behave badly to each other. People working together in a newspaper office are not supposed to get into punch-ups in the newsroom because they disagree about how something is worded or whose turn it is to make the coffee. Nor are volunteers working at the animal rescue centre allowed to start screaming at each other over who left ferrets in the filing cabinet or the corn snake in the cutlery drawer. In fact, there's pretty much nowhere where people working together to do something good are allowed to get into fist-fights, shouting matches, hair-pulling or name-calling; the same principle applies here.
Try not to get too intense. Passion can be misread as aggression, so take great care to avoid the appearance of being heavy-handed or bossy. Nobody likes to be bossed about by an editor who appears to believe that they are "superior"; nobody likes a bully.
Take a Real-Life check. Disengage by two steps to assess what you're about to say (or have just said). Asking yourself "How would I feel if someone said that to me?" is often not enough, many people can just brush things off, and it's water off a duck's back. To get a better perspective, ask yourself: "How would I feel if someone said that to someone I love who cannot just "brush it off?" If you would find that unacceptable, then do not say it. And, if you have already said it, strike it and apologise.