Start with the views you need, then work out the number of cameras. A four-camera box is not a survey. The right quantity depends on the property layout, the purpose of each view and the detail that needs to be visible in a recording.
Make a simple coverage list
Walk around the property and list entrances, access routes and areas you want to review. For a home, this could include the front door, driveway, side gate and rear access. A business may also have a delivery door, counter, stock room, parking area or loading bay. These are planning examples, not a recommendation to record every area.
Separate overview from useful detail
A wide image is good for understanding movement through a scene. A closer image may be needed to see what happened at a doorway or counter. Trying to do both from one distant camera can leave an attractive overview with too little detail where it matters. Higher resolution does not remove the need for an appropriate lens and position.
Check what blocks the view
Open doors, parked vehicles, racking, garden plants and displays can hide activity. Consider the property as it is normally used rather than only when it is empty. Think about the view after dark too: lighting changes, headlights and nearby reflective surfaces can affect recorded detail.
An example planning exercise
For a home with a driveway and separate side gate, you might begin by listing a driveway overview, a front-door view and the side-access route. At survey, it may turn out that one camera can cover two of those purposes, or that the door needs a separate close view. This example illustrates the process; it does not establish a camera count or price for your home.
For a shop, an entrance view and sales-floor overview may be a starting point, followed by the till area and stock-room access. Tall displays or several rooms can change the requirement. The question is whether an authorised manager can follow an incident through the relevant space.
Leave a sensible expansion path
If the property may change, discuss spare recorder channels, PoE power and cabling routes. Spare channels alone are not enough if the recorder or network is already at capacity. Expansion should be planned where useful rather than paying for cameras without a defined purpose.
Bring the plan to a survey
A sketch with entrances and desired views is enough to start. Note the places where cabling or access may be difficult and who will use the system. Read about home CCTV, commercial CCTV or guide installation costs, then arrange a free survey to turn those requirements into a specification.