If you can't see them, just toss your fly into the shoreline shallows often enough and you are sure to be near a bed. When your fly hits the surface on or near a bed, a bluegill will be quick to rise to the occasion. They are fearless. They have the traits of a junkyard dog. It floats well, and when you twitch it the legs will flutter seductively.
Bluegills have a hard time turning it down, and it is inexpensive compared with more serious flies.
About the only thing you need to do is to test colors. I carry everything from black to orange. Most days it really doesn't matter. They also will gobble up small poppers, dry flies, wet flies, nymphs, imitation ants, grasshoppers, crickets. They aren't choosy.