More important than fly selection or color IMO is the retrieve if you are
fishing a wet fly. It needs to be painfully slow to an order of magnitude. Flip
a small white wooly bugger out and let it sink for 15 or 20 seconds. Then
start lifting the rod at the rate of about an inch a second, if that fast.
Then wait for the faint "tunk" and haul him in.

I use this technique to outfish my old man, the best bait crappie fisherman in
the western hemisphere.

S-L-O-W