Do not insult the vandals. Most "vandals" fall into one of two categories: newbies who do not know any better, and true vandals or trolls. Getting angry and insulting, deriding, or verbally assaulting them is usually what trolls want from you, so as to play up into a flame war, and will potentially alienate newbies who could become useful future contributors. Insulting vandals can also be considered harassment.

Another way of saying this is: render good for evil. (That might sound familiar.)

It is important to note that in dealing firmly with a conscious vandal you may be doing what is necessary, but most often paying any attention to them other than warnings and reverting their vandalism is called feeding the trolls. Vandals and vandalism should be corrected by blocking and reverting or protecting. The key is to not do these in a way that is more harsh than need be. For example, after a string of vandalism and warnings, blocking a user with a summary of "GO AWAY" is likely to make the vandal try again and see if they can get another strong reaction. Remember: Revert, block, ignore.

Many users keep their cool by using predefined templates to warn vandals. These, while not suitable for every instance of vandalism, help by being terse and to-the-point with no added emotions: "You're vandalizing, stop or you'll be blocked". Likewise, many users use short and effective block summaries when dealing with obviously vandalous, trollish accounts ("user...", "{{UsernameBlock}}").

The reasons for this are simple:

• The vandalism label is often too readily applied. Vandalism "patrollers" have to deal with the flood of recent changes, vandalism or not, and make quick calls on edits. Frequently they make incorrect ones. Anyone who has been a user, especially a bold one, for some time has probably had at least one legitimate edit of theirs reverted as "vandalism". Incorrectly accusing someone may be biting a newcomer or annoying an established user. By insulting them at the same time, the damage is made much more severe.
• Insulting vandals is the surest way to increase vandalism. If someone is doing something they know is wrong, insulting them over it is likely to make them vandalize more, just to get that reaction. If someone does not know what they are doing is wrong, then insulting them is likely to create disruption unnecessarily. This is similar to trolling.
• Keeping back from insulting vandals is a way to keep vandalism from happening, not only because an argument requires two sides but also because your restraint, being exactly the opposite of what a vandal expects, might stir up remorse and even repentance.
• All but the most hardened, dedicated vandals can do an about-face (maybe not immediately). Try to approach some of the borderline cases with a suggestion before jumping right to {{uw-vandalism4im}}, and the possibility exists they will decide to contribute helpfully.
• Being nice is a nice way to be! Remember the motto: It's nice to be important, but it's more important to be nice.