Trim trees so that limbs don't provide a means of getting on roofs or second stories, or of getting over a wall or fence. Trim tree canopies to at least 8 feet to allow visibility into your property. Trim bushes to less than 3 feet to eliminate possible hiding places, especially near windows, sidewalks, and exterior doors. Make sure that trees and bushes do not block lights. Plant bushes with thorns or prickly leaves under ground-level windows to make access more difficult for burglars and along fences and walls to make climbing more difficult and prevent graffiti.