to keep one's eyes open for all possibilities; to be alert and observant; literally to look in all six directions

Literally meaning "the eyes see in six directions and the ears listen in eight directions"; describes being sharp-witted, alert, and able to stay informed of everything happening around oneself.

(idiom) to have sharp eyes and keen ears, literally describing one whose eyes watch the six roads and ears listen in all eight directions

to have a sharp ear for sounds coming from all directions; to be alert and observant