I press my seams on the back with a dry iron to set the seam then flip the block or quilt over and spray lightly with a diluted starch and press well. So far so good except with pinwheels. Those are little more troublesome.

There are also videos on how to do multiple seams (like the pinwheel) where you just snip a few threads, push your finger into the middle and they fan clockwise. I used this method for a "Quilt in a Day" and it worked beautifully.

That Pesky 1/4"
 

Thank you all for the great ideas! I've heard of the one that Eleanor Burns teaches where you snip some stitches and form a pinwheel of the seam but I've never seen a video on it. I will check it out. Thanks all!!

This clip shows nesting seams and the method where all seams are pressed into the same rotation. The center creates a flat piece. Using this method on a pinwheel creates a swirl

http://video.about.com/quilting/Nest...uilt-Seams.htm