Again, to keep this blog shorter, I will start right away with my standard sharpening settings. There are lots of tutorials and videos on sharpening images in Lightroom. Please, google and check a bunch of them to learn more on various adjustment sliders and various sharpening strategies. You really should check many of those tutorials because there are good ones and bad ones. My method is different from many others. It is part of the look I want my images to have when printed.
There are two important things to notice: (1.) There is no single right way of sharpening images as it all depends on the look you aim for. I show here what I like, you may prefer a different look. (2.) Sharpening is not affected just by moving sharpening sliders in Details window. "Sharpness" is also affected by your camera exposure vs. Lightroom exposure, contrast settings, color saturation, clarity and noise reduction. The way we visually experience "sharpness" in an image is a combination of several factors. What you especially should notice in Lightroom is the importance of Clarity slider and how sharpening and noise reduction always (not just in Lightroom) fight each other.
It is important to know how these sliders work. Also you should check what value of Color Noise Reduction is best for your camera. Set Luminace and Color to 0 and increase Color just to the point where noise becomes black and white in grayish areas. From there any higher value starts to eat small color details in image. So, play with those sliders and learn to see what happens in your image. If you keep Alt/Option pressed, you can see a black and white presentation of the effect of the slider you are moving. It may help but remember always that every image is a sum of many factors. Touching one affects also the others.
When ISOs get higher, I increase slightly both Amount and Luminance to balance detail and grain. It may sound strange but it actually works. Only move both hand in hand in small steps (+5 mostly at a time). At ISO 1600 I very seldom go even to Amount 50 / Luminance 25 for correctly exposed Olympus RAW files. Everythings else stays at my "default" before I find this initial balance.
Sharpening is a Two Step Process
One of the beautiful things in Lightroom is how it obeys the two steps of sharpening. The first step is doing it visually right. Visually right means that you like it when seen at 100% on a calibrated monitor. Only avoid creating unwanted problems like distracting halos. Typically they result from too high values of Radius.
The second step is sharpening for the final size and media of presentation. Media may be here monitor or print etc. These are taken care of when you Export or Print your image. There you choose the final size (and resolution) and respective sharpening for media. Lightroom does the technical part automatically. There are three Amount levels to choose from: Low, Standard and High. Start with Standard and you are safe. I prefer High for some Matte printing papers, but that's the only exception I use.