Black and white conversion is one of those things that looks simple and isn’t. The difference between a flat grey image and a genuinely compelling monochrome photograph is almost entirely in the conversion approach and the post-processing judgment.
What most preset packs get wrong: they apply a single luminosity formula without accounting for the original colour relationships in the image. A portrait shot under warm tungsten light needs a completely different B&W approach than a midday outdoor street photograph.
For Lightroom users: the B&W mixer panel is the most important tool. Pulling the orange and red luminance up dramatically for skin tones in portraiture is almost always right. It recovers the skin detail that a flat conversion buries.
For Capture One users: the colour editor in B&W mode gives more precise control and the film emulations are better than Lightroom’s for certain styles.
Free alternatives worth knowing: RNI Films has a free tier. VSCO had a period of good B&W presets that are still floating around.
The most useful filter for physical black and white photography (when shooting on digital and simulating it): understanding what coloured lens filters do to tonal relationships. A red filter darkens blue skies dramatically. A yellow filter is more subtle. Replicate this in the B&W mixer.
What’s your current B&W workflow?