I serge edges and prewash without soap. I fold as soon as it comes out of the dryer and don't iron until I use it. I've heard that MOST of the shrinking happens in the dryer. Don't know if it's true, because who wants to measure WET fabric? I use fabric sizing when I iron, because I don't want to deal with the bugs that are attracted to starch.
I also soak cotton batting and then dry it in the dryer per Harriet Hargrave's instructions. I've never wanted the old fashioned look, which you can get by NOT pre-shrinking cotton batting.