I have watched several quilters on You-Tube and Jenny Doan from MSQC, when they press the pieces they have sewn, the press from the top. The put the piece down with the light side down and then press pushing the dark side over and the seam. So this is how I usually do it unless I want an open seam then the only way to do that is pressing from the back side.
If you are talking about ironing the entire quilt before layering it to quilt, then I iron from the back side first, then flip it over to iron it a second time to make sure there are no pleats or wrinkles. And for those difficult seams that just seem to want to go the wrong way I have been known to use a glue stick to keep them in place.