As with so many questions, the real answer this is 'practice', but the following steps may help you in the right direction...
- Firstly, you need to start off with an image that has been shot in the correct way. In the case of your example image, this would mean shot in a dark environment with lighting to pick out just a few facial details.
- Then take the image into photoshop and increase the contrast (using brightness and contrast, levels or curves, whichever you prefer) so that just the basic shape of what you want to see remains.
- Finally you need to work over that overly contrasted image with one or more brushes in various shades including black and white and at least one shade of grey to 'mess up' the edges and add or remove detail as required. While doing this, you will probably need to have the original image on hand to reference back to.
Depending on your approach and style, you might end up using some or none of the original image in your final design. I would suggest that you want to get to a point where you are discarding the entire original image so that everything you are left with is what you have drawn.
Other than that, just repeat the process again and again until you get good at it.