Nikon D300 Focal length multiplier is 1.5 so 50/1.5 = 33.33 which is closer to 34 not 32 but it's close enough. 18-55mm lens is a good basic good lens but if you want to be sharper then the AF-S DX Zoom-NIKKOR 17-55mm f/2.8G IF-ED or AF-S NIKKOR 24-70mm f/2.8G ED is way to go. If you think it's too expensive then you might want to consider renting it.
Use F-stop of F 5.6 and up is and lonf exposure best for landscape. http://www.photozone.de/nikon--nikkor-aps-c-lens-tests/231-nikkor-af-s-17-55mm-f28-g-if-ed-dx-review--test-report?start=1http://www.photozone.de/nikon--nikkor-aps-c-lens-tests/236-nikkor-af-s-24-70mm-f28g-ed-review--test-report?start=2