A long time ago, longer than I care to admit, I used color filters for my B&W photography. Carried those darn things with me everywhere. Suffice to say this was way before there even were digital cameras.
It was fun to fool around with them and it taught me a great deal about B&W photography. Lessons that were particularly useful to me later in life, when I entered the wondrous world of Photoshop. What color filters do is, simple said: they lighten colors that have reds such as yellow, orange and magenta in them and they darken green and blue.When used correctly, they gave a lot of control over the outcome of the B&W photography.
My B&W processing these days is nothing more than a computer simulation of color filters. Manipulate contrast. It gives a far more realistic and playful result than simply desaturating a photo could ever give you.
B&W
This is my SOOC. Father & son. I like it, but I prefer B&W photos. Always have and always will.

The next step depends on the photograph you’re editing. Different scenes call for different hue/saturation adjustments. I’ll end the posting with an overview of colors and what it is they are used for in B&W photography.
Open a new adjustment layer in the layers palette and choose Hue/Saturation.

The next step is critical to the outcome of the B&W.
I opted for a (rare) blue (+45) because this will obscure distance and add an almost atmospheric perspective to your photo. It also mellows the contrast a little, which is what I was looking for. Set the layer opacity to 60%.

This is what my photo looks like now. No worries, it’ll all be okay. I promise. No, really!

Time to add some B&W. Add another adjustment layer and choose Channel Mixer.

The channel mixer box will pop up.

Check the Monochrome box and now we tweak the B&W a little. I gave Red +12, green +65 and blue +12.

There’s that mellow contrast I was looking for, but still with enough depth to make it interesting.

The photo needs light, so let’s add it.
Add another Adjustment layer and go for Curves this time.

Grab the line and drag it up. That makes things much lighter. Play with the opacity of the layer. I set mine to 80%.

Now we’re talking. But we’re not there yet. Basic B&W can be beautiful, but it can also be flat. Lifeless. I like to add a little hint of color to my photos.

Add another adjustment layer and choose Hue/Saturation once more.

Check the Colorize box, drag the saturation to 8 and find a tone that works for your photo. I’m partial to yellow and greenish tones so I’ve set mine to 50.

That instantly added a little life and softness to the photo. See what I mean?

I finished the photo with a Light Vignette, a little sharpening and a border. That was it.

Color Filter Effects:
Red: Darkens skies and lightens skin tones.
Orange: Similar to a red filter but with a less intense contrast. Perfect to increase the drama in landscape photos.
Yellow: Basic light adjustment used to make B&W photography more natural.
Green: Creates bigger contrast between shades of green. Used for foliage.
Blue: Decreases contrast and dims the distance.