There are tools that many photographers neglect and this is one of them. The histogram is criminally underused, possibly because it isn't all that intuitive to beginners, but once you understand how to read it, it can keep you from making costly mistakes.
There was a lesson I learned rather early in photography, but I didn't apply the right weight to it. In fact, I kept learning the same lesson — albeit less frequently — for a few years after I first started. This lesson was that the LCD on the back of your camera cannot be trusted. What I mean by this is that if you simply look at a picture you have taken on that screen, you can miss all manner of issues. For example, it's easy to miss the fact that your subject isn't perfectly in focus, or there is some motion blur, or you have blown highlights or crushed the blacks, and so on. The first two issues can be discovered with some zooming in, but the latter two have a far more reliable safety net: the histogram.
There are a few types of histogram, but the only one I use regularly is the luminosity histogram. If can learn to read this — which I assure you is easy to do — then a quick glance at it can reveal to you fatal mistakes. Not only can it tell you if there are any pure black or pure white pixels in your image (which would contain more or less no information), but it can also give you an overall sense of how well exposed the overall frame is by the position of the bulk of what's displayed in the graph.
Histograms are one of the driest pieces of education in photography, but are a worthy investment.