When you take a photo, you can check the image on the screen. Most people simply check for a second or so to see that the photo came out reasonably ok, but don't forget you can also use the magnify button. Why would you do that? Because in portrait and wildlife photography it is critical that the eyes are sharp. If you magnify and find the eyes aren't sharp you have time to take another photo and ensure that you correct this. It is too late when you get back home, no amount of sharpening in Photoshop will correct out of focus eyes.
Next, did you know that on DSLR's you can usually set the camera to warn of bright highlights. With this feature, any parts of the image that are overexposed will flash. This is useful to check that a face or a sky is exposed correctly. If highlights are a problem set the camera to underexpose slightly and try again.
Then there is the histogram feature which many people do not understand and therefore do not use. A histogram is simply a graph of all the tones in an image displayed from dark tones at the left to bright tones at the right. For an average image you would expect to see something like a hill with the curve rising from left to middle and then falling again. But the histogram depends upon the image. A dark interior will skew the histogram to the left and a bright sunny beach will skew the histogram to the right. Once you learn how to interpret the histogram you can check to see if an image has turned out as expected or if it needs a little underexposure (skewed right) or overexposure (skewed left).
Finally, don't forget to check your composition using the screen. It is much better to compose in camera that spend time cropping or trying to recover a photo later.
So keep your eyes on the screen.... and this website !