I like simple hen feathers for wings. Whiting used to have 'Wingers', but no longer breeds them. That's OK, because I have a lifetime supply huge selection.
For tails, I mostly go with Whiting CdL tailing paks. For hackles- Whiting capes and saddles. For bodies- fine dry fly dubbings and various furs, sometimes synthetics for subsurface emergers. If they are out of tailing paks, buy a Whiting CdL saddle- tons of tailing hackles- color them with felt pens.
Here's a photo of what I'm putting in my boxes now, with a few bodies started. I judge a dry fly for proportional balance, and then for natural floatability (tank test), and then for looks after applying floatants. If a fly collapses or gloms up after applying floatant, do something different.
Mayflies 2- 800.jpg