In the same way that a studio photographer lights his subject, so does the landscape photographer. The only difference is that a landscape photographer does not have the privilege of moving the light himself but has to be alert until the perfect light presents itself.
Observe what the light is doing and plan your shot accordingly. The more time you spend into the field, the easier it becomes to predict what the light will be doing.
It was an overcast rainy day when I was driving by Dingli cliffs. I saw little pockets of white light diffuse through the clouds and I knew that at some point they would illuminate Filfla the way I wanted it. I spent little over an hour watching the little pockets of white light dancing across the sea when finally it happened. I was already set up. The settings were easy; F11, ISO100, 1/400th of a second shutter speed.
This may not be a portfolio piece but definitely a shot worth waiting for.