Always check that the bonnet is closed and securely locked:
A bonnet that is not closed and securely locked is dangerous as it could fly open while the vehicle is moving and block the driver's vision which could result in a serious accident.
Use only windscreen washer fluid or plain water in the reservoir:
Using radiator antifreeze as washer fluid is dangerous. If sprayed on the windscreen, it will dirty the windscreen, affect your visibility, and could result in an accident.
Inspect fluid level in the washer fluid reservoir; add fluid if necessary.
Use plain water if washer fluid is unavailable.
But use only washer fluid in cold weather to prevent it from freezing.