I wrote recently (here) about a simple, quick, very effective way to convert color photos to B&W in Adobe Photoshop.
This morning I laid out the weekly newsletter of the Ananda Community of Mountain View. I wanted to use the following color photo:

Alas, the newsletter is printed in black and white and the printed photo looked crappy. The faces in shade were black and the people were merged with the visually busy background.
A preliminary note. I had processed the color photo with Photoshop, using the paid Perfectly Clear plugin which enhanced the sense of depth.
I first tried converting the photo to B&W using the usual lazy method in Photoshop: Image > Mode > Grayscale. But it still printed horribly.
Then I remembered the article referenced above on converting color photos to B&W in Photoshop.
I first chose Image > Calculations. Here are the settings I used:
Finally, I converted the photo to a duotone in Photoshop:
Image > Mode > Grayscale (converting to grayscale at this point will not degrade the photo)
Image > Mode > Duotone > Type: Quadtone. And for Preset (click to open the drop-down menu) I chose Bl 541 513 5773.
Here are the Duotone settings I used:
Here’s the final image; it printed WAY better on my bog-standard B&W laser printer (Brother HL-L5100DN). I raised the shadows slightly in Photoshop with Filter > Camera Raw Filter: