There is one little setting that is so very often overlooked in Lightroom and it's a setting that can make editing quicker and easier - Lens Correction.
Some camera lenses will do weird things to an image, like wide angles can make people or building lean into towards the center of an image. Or, it can stretch subjects wider who are on near the edge of the frame. Some lenses, like my Nikon 60mm f2.8 macro, will put a vignette on the image. Vignettes are an effect many photographers add to an image to help make the subject more of the focus to the viewer, however a lens vignette can be overpowering and greatly darken the overall image.
Below is a simple example of the quick, simple, and positive effect lens correction can have (not one other thing was done to the image).