Michael,
As all of my fishing buddies know, my "go to" fly is a yellow woolly worm with grizzly hackle & a red wool yarn tail. I tie mine on a TMC 200R curved nymph hook (mostly size 12) & it is DEADLY for big gills, although it will also catch about anything else. I got brown trout in Virginia's famed Mossy Creek on one. BTW, I also got a gill or 2 in your fine State's Lake Moultrie on one.
When dry, it will float for a second or 2...let it lay & give it a very short strip (if needed) & it'll sink. I fish it letting it dead drop, then a strip, then let it drop & don't be afraid to vary the retrieve....try to keep it s..l..o..w.
Mike