I don't prewash except for swaps and certain dark fabrics and I will continue to do so. My choice - I tell beginners to wash.
<how do you keep the fabric from fraying and tangling in the washer and, after washing>
Wash on delicate cycle. There is no need to go through an entire wash and beat up your fabric. A lot less strings. Also, Rubesgirl, I love the quilt in your avatar. Is that all it is? H's? What a happy quilt!