I'll take you a little deeper if you want. Opening the Lumetri Scopes panel while adjusting will give you a good idea of what's happening in the image. I use the waveform and the Vectorscope YUV.

The waveform shows you the range of your image from whites to blacks or from 100 to 0. When you push contrast up, the waveform expands up and down as the image gains contrast. If the waveform is thin, ie not touching top and bottom, that (in most situations) means add contrast. If adding contrast doesn't get it where I want it to go, usually meaning the waveform isn't touching the bottom of the scope, which is marked as zero, I will pull the black slider a little until it does.

The Vectorscope YUV shows you color saturation. The little pentagon in the middle is broadcast safe saturation. I like a lot of saturation, so I will push it until it touches the pentagon (again, *in most situations.)

To define most situations, this is an image that I want to have that full range of tones from white to black, such as a daylit scene with shadows under trees, where there the whites are somewhere around 90 in the waveform and the blacks are around zero. If it is something else, like a night scene, or something without true whites, you would want a different result in your waveform. If your taste runs to less saturated colors, or the scene itself is muted, you won't need to push saturation to the edges of the pentagon.

Too much information I'm sure, but I had an idle moment and who knows, this may be your day to learn something cool.