It depends on the pattern I'm making which way I do seams. I've been taught if lots of seams...press open. I've also been taught press (never iron) to the dark side (no dark side just pick a direction). Then I've been taught to nest (one way then the other way). There is no right way or wrong way. Sometimes the seam will "talk to you" about which way it wants to lay (sounds crazy I know). Remember there are no quilt police and whichever way you decide to do your seams will be the "right" way for you. Just relax and enjoy the quilting experience!
Anita