There are several steps to take when trying to minimalize vandalism. Ideally, they should be taken in the following order, as needed:

1. Promote only trustworthy users to moderator status
2. Revert vandalized pages as soon as they're found
3. Ban users who repeatedly cause problems
4. Lock a page that is very important, yet is being repeatedly vandalized

Here are a few related pages that may assist you in your fight against vandalism and online abuse:

• Vandalism, Spam and General Misuse
• How to Deal With Flame Wars and Internet Trolls