Using Channels - converting to Black and White.

1. Open Image in Photoshop and make a duplicate (save the original work on the duplicate)

2. Go to 'Layer' in the horizontal tool bar:
- New adjustment Layer
-Channel Mixer (Click) -
first window click ok

second window adjust to:
select monochrome x

Then, as a rough guide try this combination:

Red 70%
Green 30%
Blue 20%

Adjust this so that it LOOKS good (how you want it) but aim at the total percentage of colours equalling 100%

3. Add Hue/Saturation Layer
(Go to Layers-New Adjustment Layer - Hue/Saturation - OK)
Click OK
Then go to Layers window and move your HUe/Saturation Layer (click and drag) UNDER the Channel Mixer (so it is closest to the background layer) - double click on the icon(black and white circle) - adjust the saturation.