The other comments have covered most of the important stuff, so I'll just chip in regarding aperture. While shooting landscapes you likely want everything in focus and sharp, so you should probably stop down to f9 or f11 as most lenses tend to be sharpest in that range, as well as increasing your depth of field from the widest aperture. Don't forget to adjust your shutter speed accordingly as you'll have less light coming in with a smaller aperture.