One of the biggest mistakes I've seen beginner photographers make (and that I most certainly made when I was starting out) is to use the LCD as a means to check the exposure of your photos. I get it, you can see the photo and quickly tell whether it looks "correctly exposed" or not. Well no, that's actually not true. You see, the LCD screen is only meant to give you a quick preview of the photo and can be used to check composition. However, for the best and accurate representation of the values in your photograph, you'll want to be using your camera's histogram. This will give you a graph that can tell you whether you're under or over exposed, and if any highlights or shadows are getting clipped, which will save you a ton of work later in post.
One of my favorite blogs to follow is Digital Camera World, and they have many articles on using and understanding histograms. However, this particular article has a great cheat sheet. And who doesn't love cheat sheets!
I also found the following video by Joshua Cripps which offers a great explanation on the basics of histograms and how to use them in your photography.
Hope you enjoy and please share and leave me a comment below if you have any questions or tips!