I starch just before using a fabric for a project. First I wash it by color groups with a little detergent that I will be using in the future (to be sure any bleeding is eliminated) then when it is still wet/damp, put it in a painters tub with Sta Flo 1 to 1 mixture. I let it soak while I wash the next color set then I gently/firmly squeeze out (never twist) what I can (if it is a really large group of fabric, I sometimes ask my DH to squeeze it for me (he has really big hands) then I put it in the dryer and dry it really good. Now I know I won't have any more shrinkage. When I press it, I just use water in a spray bottle. Everything works better for me with this process.