It is difficult to be prescriptive about these things, as all files are different. I would say that usually as little as possible is good policy. If you are getting halos along points of high contrast on web images, you know its too much. I rarely go above an amount of 50 and radius of 1. The think is to experiment, and don't let it increase the contrast too much either

I have a book on Elements 3 which suggests as an "all purpose setting" Amount 85%, Radius1 Threshold 4. For soft subjects (flowers, puppies,people etc) Amount 150%, Radius 1, Threshold 10. Portraits (head and shoulders) Amount 75%, Radius 2, Threshold 3. Moderate sharpening (product shots, landscapes) Amount 225%, Radius 0.5, Threshold 0. Maximum sharpening for slightly fuzzy photos Amount 65%, Radius 4, Threshold 3.
I have only used the all purpose and it seems to work well as just that.

It seems that my approach is much the same as Stephens. Generally the amount is kept below 50 with a radius of 1. Keeping an eye on any areas where the local contrast starts to increase dramatically. The threshold I keep between 0 and 5 dependent of noise levels in the image.

Over the years as I've upgraded the quality of the glass the degree of sharping I need to do is much reduced compared to budget glassware shots.

This pretty well falls in-line with Mike's Figures from the book.

I have just posted a thread about the Picture Style settings in my 1D Mark II N, which I’m trying to understand.

According to page 53 of the manual, the parameter settings (sharpness, contrast, saturation, colour tone) available in the Picture Style options, DO have an effect on RAW images, although I haven’t verified this yet.

I have replied to your other thread Paul. Essentially though whilst I accept the POI I would question the need to use these parameter settings if using Raw

I use PS7 USM. If I'm going to use neatimage I use the USM until afterwards.

Do you find though that this can negate some of the work Neatimage has just done.

sometimes .. i use the duplicate layer ... high pass ..hard light about 15% .. opacity slider 20%.. merge down layers as an alternative to usm

It probably puts a little noise into the pic, but not enough to cause a problem. I find that Neatimage tends to make the picture look phony and flat if Im use it to remove all the noise. I frequenty set Neatimage to remove only half the noise bcause I like the look of the finished product better that way.