Make a few versions of the same block varying where you place the light, medium and dark fabrics. You will see how the placement affects the final product. Sometimes I make a block and think - ick. So, I've been known to take blocks apart and either change a colour or intensity of the same colour. I am a very far cry from being a natural but have learned that it does get easier.
Try making a couple of small mystery quilts. They force you to work with value - light, medium, dark - contrast. Lots of great learning in them! You can find some mystery quilt patterns right here on this board if you look up paintmejudy and her mystery train rides. Here, I did it for you:
https://www.quiltingboard.com/search...archid=3073257