I use pieces of nightcrawler, just big enough to cover the #4 hook (plain hook or jig hook). I have kept nightcrawlers in my fridge for a couple of weeks, just in the "dirt" they come packaged in from baitshop/Walmart. But, they don't do very well after a couple of weeks. They start getting puny and eventually die. They would probably do better in a larger container, with real dirt & dead leaves ... & something to eat ... and in a "cool" place, rather than a "cold" place.

Strange as it may seem .... I tend to catch Shellcrackers on the dark brown/thick end of the worm & Bluegill (most of the time) on the "pale tan" end of the worm. (maybe the Shellcracker think it's a snail ??)