I also don't wash my fabrics beforehand, none of them but I do dunk them in a tub of starch, wring them thru a home-made wringer to save my hands and hang to dry. Then mist them with vinegar and water to press. As to seams, have you tried the twirling method where the seams will go in the same direction all the way around? True, it won't always follow the rule of pressing to the dark side but to keep the seams at bay where they all meet together, it does a pretty good job as there's nothing like having a large bump in your quilt top when you go to quilt over it. I know my machine doesn't care for it none.