I prewash everything, fat quarters included, and never serge, clip, or otherwise mess with any kind of 'edge prep'. I simply use the gentle cycle on my top loading washer. It's the full cycle agitation that tangles everything and frays the edges.
Trim any long threads before tossing in the dryer and you're good to go. I haven't had any tangled, knotted, excessively frayed, twisted up fabric for years...not since I've been washing them this way...and they don't come out of the dryer all wrinkled up either. Gentle cycle is enough to remove all sizing and chemicals for dyeing or fusing or anything else.