I agree with the lady who lets the pattern tell her which way to press. Definitely you press open if it is a star or something like that. I was taught to piece by hand many years ago and we were taught to press all seams open. I don't do that anymore so don't know if that is still the rule. Straight seams I press to the dark or if a lot of 2 1/2 inch strips, I press all in a block the same way.