I use both methods, press to the side or press open. Depends on the project and how many seams are coming together. There is no right or wrong way. When pressing open and trying to line up seams I either use a double pin or I pin on the down side of the seam. I match up with a pin in the seams themselves then use another pin to pin together on the side that will be sewn last as you run your stitching line across the intersection. Clear as mud?