Excellent sharpness is one of the top requirements for a successful landscape image, and there are steps you can take all throughout the process of shooting to help ensure that your image is pin-sharp. This excellent video gives a great seven-stop process to help you get those sharp photos.
Coming to you from Chris Sale, this fantastic video details a seven-step process for ensuring your landscape photos are as sharp as possible. One mistake I often see beginner landscape photographers make is selecting too narrow an aperture. It is true that lenses are typically sharper when stopped down from their maximum aperture (they are normally sharpest about four stops past the maximum aperture) and that you gain more depth of field as you stop down, but past a certain point, you begin to run into issues with diffraction, which will rob your images of sharpness. If you need more depth of field and/or sharpness at this point, it is best to look into techniques like focus stacking. Check out the video above for the full rundown from Sale.
And if you want to continue learning about landscape photography, be sure to check out "Photographing the World 1: Landscape Photography and Post-Processing With Elia Locardi!"