First thing I do when I come home with new fabric is "head to the washer". NOTHING goes into my stash until it is washed, pressed and blocked. Here's a demontration I found to explain "why" and to assure that you have a "straight of grain". Hope this helps.
http://janeweston.blogspot.com/2008/...ready-for.html
She's using a small piece. If you have 2 or more yds. of fabric. Place the fabric on your ironing board lining up the salvage (fabric hanging over both sides of irong board) as she shows and work from the middle of the fabric to one end. Then repeat from the middle and work to the other end of the yardage.
I "never" use starch or any additive when I do this. You never know how long the fabric will be sitting in your stash and how this could affect the fabric