They can help you predict what the best times and locations are
Use a polarizer if beneficial
It can help with haze and increase contrast.
Settings
Image Quality: Shoot Raw if possible
It lets you get the most out of what your camera sees, because you can bring out detail in highlights and shadows more easily
If you cannot shoot Raw, shoot large, high quality JPEGs(Low compression)
Shooting Mode: Aperture Priority or Manual are probably the best for landscape shooting modes
ISO:
Use a low ISO setting if possible
It will give you less noise in your shots
Aperture: Mostly you will want to use smaller apertures to have sharper images with more depth of field, unless you are including something in the foreground.
Metering: Use evaluative/average metering
Drive mode: Single shot mode
Autofocus, probably, although you could use manual focus as well
Time and Light
Sunrise and sunset are great for interesting light, but you can do nice images at other times
Sidelight can be good to show contrast and texture
Backlight is good for transparent objects and silhouettes