[Oni]

Another tip is to unplug any appliances you aren't using. Typically these things will imitate another appliance, like an alarm clock or smoke detector.

the infrared ray of the camera must hit your phone's camera to be able to see it

In that case, dedicate an entire day trying to line up the angle on both cameras.

I'd imagine you only need to do it from the angles at which you'd be requiring privacy.