So Pete says to start with a detail of 80 and Martin says to start with a detail of 15. Wow, that's quite a difference of opinion!
Personally, my experience has been that neither of those suggestions works well for me as a starting point. I find that a detail of 80 is frequently way more than necessary and will sharpen any and all noise in the image, especially if the image was shot at anything other than base ISO.
I also find that a detail of 15 is too low, as LR wont' sharpen any fine texture. Frankly, when I start out, I'm culling first and in my first pass of culling, I'm assessing critical sharpness, so I need to see all the details.
So, I like to start with something like 35 for detail and amount around 60 or 70 so that I can see the edges clearly. Later, when I'm editing the photo, I'll adjust those settings, possibly reducing the amount. With higher ISO images or with portraits, I'll often lower the detail to 25 or 15 and with landscapes I sometimes crank up the detail to 40 or 50. After 50, LR implement deconvolution, which just doesn't seem necessary to me with my X-T2. My X-T2 images are already very sharp by detail of 40 or 50. (In contrast, my Nikon D800, which had an AA filter seemed to benefit much more from higher detail settings.)