fishpinner, good going. I've been hiting some south OP lakes and doing well with size 10 beadhead black sparkle buggers. I tie 'em up with a tail of black marabou, a body of black pearl new age chenille, and some black saddle hackle...don't even need any crystal flash.

Damsel Nymphs in size 10 are also working.

A beadhead bugger tied with a body of halloween new age chenille, brown marabou tail, and either black or brown or olive (all three work) saddle hackle also works. Size 10 has been working for me.

Dragon Nymphs (Try Skip Morris' "Furry Dragon" or his "Predator" (which is a brown foam bodied thing that could be either a water beetle or a dragon nymph).
The "Predator" floats, and is best fished on a full sinking line allowed to sink to the bottom...as you strip the fly back, it darts toward the bottom, like a dragon nymph or water beetle might. Slays 'em!

My favorite lake line for buggers and nymphs is a full sink clear intermediate.
Avoid the trolling lanes, and work the dropoffs, weedy shoals, edges of weedbeds, sunken logs, and old creek channels (if the lake is an impoundment).

For dries at dusk, I have had good luck with a size 12 Black Gnat, as it provides a good silhouette. This when those dark brown caddis or alder flies or flying ants have been hatching. Cast to the risers.
Also, try a callibaetis emerger, fished in the film, when the callibaetis mayflies are hatching.
Good luck...I'm still putting my act together...no expert, but this is what has worked for me.