1. What you protect
The first question is not which camera, but what is in the space. A till needs face detail. A warehouse needs width. A yard needs weather resistance. Write down the points that must be covered before you look at a single spec.
2. How many cameras
The count follows the points you wrote down. Each entrance, corner and valuable zone gets its own camera. Two well-placed cameras cover more than four random ones.
3. Which resolution
Resolution decides how much detail stays in the footage. For face recognition at an entrance, 4 MP is enough. For plate reading at 30 metres, you need more. More megapixels do not mean better footage if the lens and light do not follow.
4. Where it is recorded
The recorder (NVR for IP cameras) keeps the footage. Channel count must track camera count, and storage must hold the desired number of days. Most sites need 15 to 30 days of archive.
5. Cabling or wireless
Cable is more reliable but needs installation. Wireless is faster but depends on signal. For permanent monitoring, cable is the standard; wireless is an add-on where cable cannot reach.
6. Who watches the footage
Footage nobody watches protects nothing. Either you watch it, or you link the system to a monitoring centre that verifies events 24/7. Verification — a person looking at the picture before calling — is what separates a real event from a false alarm.
7. Who maintains it
A camera nobody cleans or checks stops being evidence. A service agreement covers cleaning, storage checks and updates. Budget for maintenance from day one.
RULE OF THUMB: If you cannot name what each camera watches and who watches the footage, the system is not designed yet.