When it comes to choosing an image that I'd like to edit into a black and white photo, I have to ask myself a few questions to help decide because not every photo is inherently a good fit for a B&W edit. Personally, I love B&W photos. I really feel that when done properly they can really create an amazing image that can connect to the viewer on many levels and make them feel emotion.
A few questions I have to ask myself:
1. Does the photo have interesting textures or patterns?
When it comes to photography, our eyes are naturally drawn to specific patterns and textures that help give those particular images that unique look. For example, jagged bark surrounding a tree or the the pits, bumps, and rough look to a stoned wall will help gain a feel for the photo without actually being able to touch it. B&W only helps emphasize those feelings and takes it a step further
2. Do the colors fit?
Surprisingly, color is one of the most important aspects in choosing an image for this type of edit. If the the colors of a photo are too close or similar throughout a photo then the image will result in a "whitewash" type look. This will give the image a very bland and mute look which is not interesting at all nor will it attract your eye to it. On the other hand, if color is wide, bright , and varied then it can become more of a distraction causing a disconnect to the viewer and more of the viewer just trying to figure out what the photo is.
3. Is there interesting lights and shadows?
While light is very important in both color and B&W photos, it is very prominent in B&W. The way light filters through the tree leaves or the shadows that fills the skin of an aged face can enhance a black and B&W photo greatly. The types of lights and shadows will submerse you a little more into the image and see detail that you could overlook in a color photo.
Ultimately, it takes practice and a little knowledge in choosing to make an image in B&W. I love these types of photos as long as they are done correctly! It should draw your eyes into the scene and give it that timeless look. These are just a few questions I ask myself and it's my general guideline to help when choosing which images work best. I suggest using these hints and ask yourself those questions. And as always, practice! It won't be long before you will develop an instinct and are able to train your eye for picking these images and editing them in B&W!