1. Black and white photography relies on the image to tell us a story. It cannot ask bright or interesting colors to contribute. This means that the photograph in black and white has to be that much better than a similar photo in color.
2. Black and white photography relies heavily on contrast and shading.
• The difference between light and dark is what often makes a black and white photo a good shot or a poor one.
• Pay great attention to shapes and tones to lead the viewer around your picture. Bright colors won't help you with black and white.
3. Weather can be you ally when shooting black and white.
• Normally indistinguishable dark objects show up against a snowy background.
• A person who is backlit (and thus dark) can show up well against a brightly lit window or other background.
• Days with poor lighting - when you may not want to shoot in color - can result in cool shadows and other effects in black and white.
• There really isn't a bad time to shoot in black and white.
• Evenings can be helpful. As the sun descends, shadows become more obvious.
4. Shoot with the lowest ISO you can get away with. The pixelation you get with high ISOs that is barely noticeable in color becomes very obvious in black and white.
5. Location matters in a black and white photo. While a dimly lit stairwell will yield poor results in color, it could produce nice shadows that will look good in black and white.

Resources

1. Smashing Magazine
2. Smashing Magazine, 2
3. Bill Emory
4. Roy V. Harrington
5. NYCLondon.com