I think you’ll find that when an image prints poorly, it’s most often because it was not a good image to begin with. Garbage in = garbage out.
Unless compression is in play, file format shouldn’t affect output quality. If you’re building your layouts in InDesign, there’s no reason not to use PSD’s. Uncomressed TIFF’s should give the same result.
Resolution is subject to the simple rule-of-thumb: linescreen frequency, (lpi), x 1.5. For newsprint linescreen frequency is almost always 85 lpi, which means the minimum apparent resolution for your images at output size should be 128 ppi. I know that sounds low, but the ubiquitous 300 ppi “rule” is most often a case of safety-margin overkill, and spread for/by those with limited understanding of image resolution as it relates to printed output.
Something that may help your grayscale images look their best is proper sharpening. Just Google Unsharp Mask and find volumes on the subject. Newsprint grayscale sometimes benefits from a judicious amount of over-sharpening.
Getting good looking CMYK in newsprint is often a matter of getting to know the specific press equipment you’re dealing with. Over/under-saturation comes easily, but a little trial and error up front can give you a feel for how much is just right.
Best of luck to you!
John M:
All of the vim with none of that annoying vigor.