You'll get dozens of dirfferent 'tricks and tips', most of which take quite a bit of extra time, put 'agitated' pin holes in your brand new fabric, waste thread and machine time, and/or don't work.
I pre-wash everything, mostly yardage from 3 to 6 yards but sometimes up to 10, and don't do anything special to it at all before it goes in the washer. I wash the unfolded fabric on the gentle cycle with plenty of water and only with other fabric, never with regular laundry. After washing, I trim any long 'thread trash' with the scissors that live on my dryer, shake any kinks out and toss it into the dryer. It comes out completely knot free, pretty much wrinkle free, and never ravels more than a scant quarter inch.
I've been washing tons of yardage this way for over 15 years and have NEVER had any of it wind up in knots in either the washer OR the dryer. People never believe it works, but that's their loss, not mine.
