If in doubt, call the utility or business in question to ask if they have sent someone to your home. Don't rely on chain locks to see who is at the door. They can easily be forced once a door is ajar. Thieves like attached garages because, once inside, they can unobtrusively force the door to the house. These are another popular point of entry for intruders.
Overgrown vegetation gives a burglar more privacy.
You can also ask the post office and paper carrier to hold deliveries until you return. Show them escape routes and familiarize them with any locks and alarm systems. If not, check with your local police for information about starting one. Robert L. Snow, Plenum Press, 1995.