What Is Best Way To Make Black and White Print?

[Ofnuts]

You can just use the Brightness/Contrast tool and add contrast, or use Colors>Auto>Stretch contrast. In both cases one problem is the uneven lighting across the page.

A better technique is to:

• Use Filters>Enhance>Wavelet decompose, decompose to the maximum levels
  
• Bucket-fill the "Residual" layer with white (this will even out the background)
  
• Layer>New from visible to get a new layer (and move it to the top)
  
• Apply Color>Levels to that layer: in the input section move the leftmost handle to the beginning of the histogram, and perhaps move the middle handle to increase contrast.