I love B&W images and when I think of a B&W image I think good strong values and contrast. I think well defined lights and darks and strong supporting middle values. For this discussion we will talk about actual B&W images not sepia and grey/white toned images.
Questions to ask:
Am I going to actually start out making a B&W image or when my image is complete will I convert it to B&W just to see how it looks and feels? Not every image is cut out to be a B&W but some that you convert can really be striking. I often do a B&W conversion at the very end just to have a look-see and sometimes I am surprised with the outcome and end up using the B&W.
Will my subject matter look good in B&W? Lets face it some images are just meant to have color and lots of it. I find B&W to be for more dramatic subjects, when I want to create a mood, or when I just want to do something different. I tend to make a lot of monochromatic pieces.
Can I mix B&W with color and still get a good final image? In my sample image I combined four major image and a few textures and overlays. The figure was originally in B&W but the landscape, trees and moon were in color. My method for this particular image was to work with the B&W and color to build the image, even adding the text and birds. I worked layering until I had the final image I wanted and then I did a final conversion to B&W using iColorama but there are many apps that will do a B&W conversion.
Do I have a good mix of values within my image? My way of thinking is that if you are doing a B&W only a portion is actual true B&W or light and dark. The majority of the image is going to fall somewhere in the grey scale and this is where your own sense of aesthetics comes in. I played with this image making it lighter and darker until I had the mood/feeling that I envisioned. What you are going for here is balance BUT that is not to say you could have an image almost 80 to 90 percent very dark and just a small spot of white/light and it would be amazing. (Something to try).
Do I have an obvious light source? Not that you need it, but in B&W an obvious light source or direction is helpful in most cases. In my sample image my light source is not obvious. It is not the moon as it logically should be. My light source is out of the picture plane. Once I decided that the major light would come from this direction I made sure everything else in the image worked - even lowering the brightness of the moon. This can be tricky and I had to add some additional shadows and lights to my model and her dress.
If you are using your own photos do you want to just shoot in B&W? I do this occasionally but most often take my photos in color.
The title of this image is “Keeper Of The Secrets”. It was created entirely on my iPad Pro using the following apps - iColorama, Touch/Retouch, LightBrush, Formulas. I personally love iColorama and use it to create most of my images. I do all my layering/combining/masking there. I used Touch/Retouch to remove any unwanted stuff that ended up in my image. I went back into this app a number of times to touch up areas. After I had an image I was happy with, it had areas of B&W and color I took it into iColorama and did the B&W conversion and added a slight blur to the model. I used LightBrush to lighten or darken specific areas of my image particularly the model. I finally used the app Formulas to add a final texture.
I am not usually concerned about what apps I use but more about the look of my final piece. Other apps that could have been used:
To create the actual image - SuperImposeX, Procreate, Affinity Photo (any layering/masking app)
To do the B&W conversion - SuperImposeX, Snapseed, Pixlr (actually any app that you can use to desaturate an image but remember if you have layers it needs to be flattened to covert to B&W)
To lighten or darken the whole image - SuperImposeX, Snapseed, Pixlr, Procreate (any app that allows you to do adjustments)
To lighten and darken specific areas - Snapseed, Pixlr, LightBrush (I LOVE this app).
To add textures - Formulas, Stackables, Distressed FX (or any app that allows layering and blend modes).