Yep, gotta be level headed. If you see someone in the yard observe, turn on the flood lights, shout or blow a whistle or air horn. DO NOT confront them.
If they are in your house you can wallop them, even if its your neighbour!
The gun laws are pretty strict. If you shoot a man that doenst have a gun be prpared to face some jail time. Do not shoot in the back either!