Alice suffered a minor electrical shock as she switched on her bathroom light. she is concerned and wants to prevent it from happening again.

what should alice do to prevent getting an electrical shock again?

Get a pull chord light switch installed in her bathroom by a qualified electrician asap. Meanwhile, keep hands as dry as possible, and try not to go near that switch until it's either been properly earthed, or whatever the problem actually is, and get qualified advice on what the problem is. Don't have wet feet either, and don't stand in puddles of water whilst operating - i she has to - the switch. 250V AC mains can be lethal, and at least painful.

None. nothing. zero. zilch.