zozee, Many quilters press the seams toward the darker fabric. Especially with white, pressing to the dark side helps the white look better from the front (cleaner, neater, more chrisp, without a shadow of the seam underneath showing). Before quilting some people even check white fabric pieces in the quilt top to see if any dark threads are laying on the whites, because stray dark threads can show through the white fabric after quilting and be unsightly.
Here's how I iron a Churn Dash, trying to keep the most seams that I can going toward the print and away from the white, while making sure to iron in a way to nest the seams of the 9-patch. (My camera is not great so I took pictures of three blocks in case the seams are more visible in one than another. .) You'll notice I didn't cut off the dog ears yet. :-)