Welcome from Florida! Values make or break a quilt. Bold contrasts seem to move, more gentle value shifts can be calming. Every now and then I see a quilt that would be just beautiful IF the person had not used all the same value, and the result did no justice to the beautiful fabric because there were no lights or darks to direct your eyes.
A piece of colored plastic can help you get used to seeing differences in values. Usually they are red or green. A pair of glasses from a 3D movie will do the same thing. Taking a picture and seeing your fabrics in black and white instead of color also makes values more apparent. Great question!