Use 'watch out for' when warning others about immediate physical dangers or hazards.

Physical Safety

Sometimes 'watch out for' can indicate being cautious about non-physical threats, like scams.

Figurative Sense

It can be used when something happens suddenly and requires immediate attention or action.

Emphasizes staying alert to emerge or happen, often something you are waiting for.

Can refer to looking forward to something desirable, not just potential problems.

Suggests the need for ongoing vigilance over a period of time, not just a single moment.