In the vast majority of my photos, I aim for one specific thing during editing.
I try to aim for filling out the histogram. However, it is very important to emphasize that this is not a necessity to make good photos; it just so happens that it works in most cases, but of course, every photo needs individual care. This tip works especially well with flat photos. High-contrast photos with one bright light source needs a bit more care. The thing a flat photo lacks is contrast, and the histogram in your editing program reveals if your photo is flat or not. If the main information is clustered together, it is flat. The idea is to use the entire histogram to add contrast and life to your photo.
A White Point and a Black Point
I most often start adding contrast to a photo by using the whites slider. This slider brightens up the brightest parts of your photo first. You can see in the example below how I only move the white slider and how the information in the histogram moves to the right. The idea about the white point and black point is to have a point which is 100 percent white and one which is 100 percent black. In this way, you ensure you use the entire spectrum of luminosity.
You can also see we have a little wiggle room on the left side, so in this particular case, we can add some blacks too. By moving the black slider, we darken the dark parts of the photo.
Here is another example where I only moved the white slider.
Holding down Alt (PC) or Option (Mac) while sliding reveals when the different values start clipping, which is something you want to avoid. Check out the example below where I overexpose the tree.
Use It Locally
In scenes with high contrast, such as the example below where the mountains are lit by the rising sun, we overexpose the highlights fast by using the white slider. I normally take care of the highlights first by adjusting them to the desired look and then, work my shadows.
By making a simple graduated filter for the foreground of the photo where I only adjust the white slider, I bring out the bright parts of the foreground without affecting the darker parts as much, effectively adding contrast and life to the foreground.
The problem about using the “shadows slider” is you raise both the dark and bright values of what the editing program interprets as shadows, which simply just brightens the flatness instead of getting rid of it. In the example below, you can see the difference between making the graduated white slider filter and globally raising the shadows.
Making sure to have a white and black point really makes your photos pop. However, as with all other techniques and tools, they are not universal rules. As an example, if your photo is a low-contrast scene full of fog, having a white and black point might add too much contrast for the photo to work. Be sure to use your critical faculties while editing and only do what makes sense.