when I learned to quilt (uh, can it be 30 years ago now - holy cow THAT went fast???) I was taught to press the seams open. later I learned to press to the dark side. you know what, it doesn't matter. it is personal preference. mine is now pressing to the side as I love the locking seams as I challenge myself to cut accurately and have corners and points match ( my motto is doing go crazy, but don't get lazy) and it is easier for me to see how I am doing when I press to the side. I don't worry too much about dark/light side - I work more on matching seams. if you are using good quality greiege goods (heavy thread count fabric) then the shadow of a light/dark shouldn't be an issue. after all the quilts I've made I never had someone be able to tell how I pressed the seams.
play, have fun and try new things, you'll determine what works best for you.