Change this area to Tone (***) and include the sections on shadows and highlights, and incluse the Clarity setting to enhance Midtone contrast. 

Ways of Converting

• Different methods of conversion - 01, 02, 03, (All have many other links)
• Pratik Naik uses a black and white conversion for initial retouching a portrait to remove the distraction of colour. He recommends that the best way of visualising tonality is to use a black Solid Colour Adjustment Layer with the Blending Mode set to Colour.. (Ref).
• Using Calculations to produce all different contrasts - 01***,
• Using Multiple Hue/Saturation Layers. Time consuming but giving the most control as lip colour can be manipulated independently of skin - 01,

Ways of Control

• Use Colour Gradients to add contrast and control - 01, [Also Gradient Maps]