Why are my photos getting so blurry?

Shutter speed is a little too slow on many of these. For more reliably sharp results, you need a faster shutter. Aperture needs to be at least f/8 to get front to back in focus. For most of these shots, a wider aperture and selective focus isn't really going to work. Familiarise yourself with hyper focal distances to get an idea of what aperture you need and the depth at which you need to focus. Landscape with a digicam is shooting fish in a barrel. With a dSLR, it's a little more exacting. Overcast conditions can give results that lack contrast and look quite soft.