It all depends on the shape and size of your space. For maximum effectiveness, CCTV cameras should watch over every entry point to your space like front door, back door, windows, balconies etc. You may also need some overlooking the main road or garden. For shops, CCTVs need to cover all the aisles and corners besides safeguarding the cash counters. Thinking strategically, you would also want to hide away some cameras in unlikely places where they cannot be easily located.