Bisch forgot #10: Shoot!
I do the same as Bisch, except I scrape off old fletching and remnants with a knife, then soak the fletching end in a dedicated can of acetone until clean. I wipe them with a paper towel, and if they squeak while wiping, I know they're clean. Have been doing exactly this for 20+ years. When fletching aluminum, I use Fletch-tite, and I dip in Fletch-laq before doing the fletching process. May be unnecessary, but by doing this I absolutely never have problems with feathers coming off.