I usually press mine to one side, usually to the darker side.
BUT - I also try to go for the least amount of bulk at the intersections, so sometimes I have to press towards the lighter side. The trick there is for the lighter side to have a seam allowance that is a couple of threads wider than the darker side seam allowance - so when it is pressed the lighter fabric seam allowance doesn't let the darker seam allowance show through.