I've fished there about 10 times this year. I just found out about it this spring and with the hot summer and drought the local smallmouth and bluegill streams have just about dried up. That has left Brookville more or less my home water. I've fished with Joe (the fellow who replied just before me) a couple times and he catches a lot of fish there so you should listen to what he says.

I've been doing a lot better the last 4 or so times there as I learn the water.

The last couple trips here is what I've used to catch fish:
Griffith's gnat size 20 and 22
Parachute Adams size 18 and 20
Hopper size 10
black ant size 14 or so
royal coachman size 18
various numphs with prince nymph seeming to be good
white midge size 22

I've found the hoppers and ants work best in mid afternoon when the sun is high. The gnats, midge, and adams work when you see them feeding on the surface. The nymphs and coachman (and other stimulator dry flies) are desparation flies. When I'm frustrated and nothing is working, I just star trying different things. I have even tossed bluegill poppers and rubber spiders. Not much luck, I did have a really big brown come up and nail a popper but I missed the hookset.

So, for my fishing, it's the gnat and midge dry flies when I see them feeding on surface, an ant or a nymph when I don't see them feeding on surface, hoppers in mid afternoon when nothing else is working (I did catch a rather large 17-18" brown on a hopper) and I just experiment when nothing is working.

Now, for your fishing style, what is working for me may not work for you. I would just recommend getting flies in the 18-22 size range and start fishing. I think at brookville size and presentatin (drift) are more important than what fly.

Last Friday, Joe and I were standing side by side and fishing very different flies but they were both small and we were getting good drifts and we both caught fish.

Jeff