Report all acts of vandalism to the police. Because many vandals are juveniles, you may not be the only victim. Documentation is important when connecting cases that may be attributed to the same individual. It will be especially important in sentencing and restitution if the individual is caught.
Clean up vandalism as soon as possible after reporting it. Replace signs, repair equipment, and paint over graffiti. The message given if they are left in disrepair is that the owner doesn’t care and it invites further damage.
Depending on your situation proper lighting, building materials (such as hard to mark surfaces), fences, or landscape materials (such as thorn or prickly hedges) may help in discouraging vandals.