Landscape photographers commonly prefer to get as much of the frame in focus as possible for maximum sharpness. Focus stacking is a common and useful technique for accomplishing this, and this excellent video will show you how to do it using Photoshop.
Coming to you from Adam Gibbs, this helpful video will show you how to use focus stacking for sharper images using Photoshop. Focus stacking is one of the most popular techniques for increasing sharpness across an image. It is a relatively straightforward concept: you take multiple images with the same framing at varying focal distances, then blend them in post so each area has the most sharpness possible. You might think of simply using a very narrow aperture, but you will start running into issues with diffraction as you get to smaller settings. Meanwhile, using the hyperfocal distance can be a good compromise in the name of efficiency, but for maximum sharpness, focus stacking is the best method of the three, and it isn't particularly difficult. Check out the video above for the full rundown from Gibbs.
And if you really want to dive into landscape photography, check out "Photographing The World 1: Landscape Photography and Post-Processing with Elia Locardi."