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 trust worthy users tomoderator status
2. Revert a vandalized page as soon as it's found
3. Ban a user that is repeatedly causing problems
4. Lock important pages that have been 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