Sharpening TIFF for print ?

I need help with sharpening TIFF for printing....I use Smart sharpen and USM....
My question is....how many turns of sharpening with USM and what amount,radius and threshold(for 16 bit TIFF)
Which magnification ratio I need to look picture while sharpening 50% ?or 100% or something else.......some pictures looks nice on 50% sharp and detailed, but when I look at 100% I see artifacts and halos and oversharpened I am concerned that halos will be visible on prints!...
Am I right?
Thanks for your kind help.

You can avoid edge halos by selective sharpening with Quick masks or Masks. Artifacts are a different story. Sharpening on a separate layer will allow you to reduce the effects and even mask in/out areas as you wish.

Robert

Marko it is not an easy subject Most sharpening will look over done before printing Actually that is the way they should look Will be lots of trial an error Do try comparing the file on your computer to the print After a while you will get a feel

An alternative is PhotoKit Sharpener Some people love it others don't I use it an can recommend

Thank you for the tips....I will make few prints with different settings and see which setting will do best.... :)....
I tought that you guys have some secret formula for that ;)

I use Photokit Sharpener for all my TIFF printing files and love it. Takes the hard work out of making edge and luminance and all the other acrobatics that you have to go through in PS to do the same thing.

Photokit Sharpener has made my life considerably easier when it comes to sharpening for printing. I recently printed a large number of photos in a wide variety of sizes. I was able to use Photokit Sharpener's settings for output on each size without having to make any additional adjustments. I had, of course, done capture sharpening previously and had done some selecting sharpening (bird's eye, for instance) before reaching the printing stage. I've gone back and reprinted many prints from the past. In the vast majority of cases, the output using Photokit Sharpener is better than my original sharpening.