There are no rules when it comes to sharpening. The strength of sharpening is up to you, and will differ depending on the content, details and textures in your image, as well as your exposure settings and ISO. In general, images with lots of high-frequency detail, like landscapes, often benefit from a lower Radius setting; while more low-frequency images, like portraits with lots of smooth skin, usually look good with slightly higher Radius settings.
While judging the right amount of sharpening, it’s always best to zoom to 100%, as this shows the actual pixels. Sometimes it can help to push the Amount slider up to 100 so that the image looks over-sharpened, then gradually pull it back. It’s easier to recognise too much sharpening than too little.…