I tied up some Caenis on size 18 and 20 hooks to fish Loriston. When the Caenis are hatching it becomes very difficult!
Anyway, they were tied "spent" with poly yarn wings tied in figure of 8 style. The body was just white (or lime green) thread and the tail was a few white hackle fibers.
Easy to tie and the lime green ones seemed to work the best.
F-Flies are easy(ish) in small sizes too.
Anything more "creative" I leave to someone else to tie.