1/3 to 1/2 a nightcrawler seems to be more effective than a redworm to me for bluegill. I use #6 Aberdeen hooks.

Walmart sells 20 nightcrawlers for $2.96. I usually buy a tub, then take them out of their original container, and transfer them into a half gallon styrofoam "crawler carrier" loaded with moistened Buss Worm Bedding. Then I put a layer of wet newspaper on top of this and let them fatten up a few days. It helps tremendously.