If you are talking about the casting bubbles that you fill with water thats my favorite set up. I use wooly worms,wooly buggers and any wet fly that works black ant/gnat etc.. during the spring and summer I use a long leader 18 inches or so with a piece of nightcrawler and make long casts with the extra weight of the water filled bubble, I have nothing but success with this setup..........its my favorite with an ultra-light rig. It works for trout also.
use your imagination and have fun, attach lures to it like the rooster tail and such.
I have also used a smaller version of the wooly worm and had really good success. It seems like ANYTHING black works quite well. I think a pretty good way to start is to buy a few bubbles and one of those 'cheapie' sets of flies (12 in a container) that WalMart sells for less than $2. There are times when I hook a fish with almost every cast. The great thing about it is that you can FEEL a hit and the fish can take line without the drag of a normal float. If you are using a floating fly, you can put unscented chapstick on the line about 6 inches or so up to the knot.
I like just about all of the micro plastics, 1 to 3 feet below a torpedo float. Tubes on jighead sizes such as 1/100, 1/80, 1/64 and 1/32 oz are good. Livebait on plain small hooks are also good. Upsize a little and tip with minnow to pound shallow crappies or upsize a little more and play with bass and channel cats.