how to make an image more crisp

[Ofnuts]

Just with the Curves tool:

• At the bottom left, the "black point" has been move to the left to coincide with the most values you have in the image (the darkest tones aren't black in your image). This increases (slightly...) the available range.
  
• Increasing contrast is done by using an S-shaped curve with a steeper increase in the tones where the detail is. The Contrast bit of Brightness-Constrast does it too, bu the steep increase is around 128 and this isn't always where the details are.
  

Done with 2.10 (which is why there is a split view) but you can do the same thing in 2.8 (without the split view).