Open a photo in Camera Raw; you can do this either in Bridge, using the right mouse key and clicking “Open in Camera Raw,” or directly in Photoshop, by selecting File → Open as Smart Object. Apply basic adjustments to optimize your image (for example, with the “Recovery” and “Fill Light” slides), then switch to the “HSL/Grayscale” tab. Check “Convert to Grayscale,” and set the Blues down to around -85. Set the Greens to +90 and the Yellows to +20.
Trees and bushes should now shine in the typical white, and the sky should appear almost black. If you want to go on and simulate some grain, switch to the “Effects” tab, and enter 15 for the amount, 20 for size and 80 for roughness. You could also apply a “Vignette.” Here I used -30 for the amount, 40 for the midpoint and -35 for roundness.
When applying a “Levels adjustment,” you can set black and white points in order to decrease color tints, but where are the darkest and brightest spots in the image? Go to New Adjustment Layer → Threshold to find those areas. This function is available under the “Layer” menu. Move the slider so far to the right that only a few white spots remain in the document.
Use the “Color Sampler tool” and set down a point there. Move the slider to the left until only a few black spots remain, and set a second point down there. One could also find a neutral gray in the image by using a “Threshold adjustment layer.” Add a new blank layer between the original image and the threshold adjustment layer, and fill this layer with 50% gray.