Jigs, and work all of the water column in a known crappie haunt. They like to suspend. If you have a flasher, look for suspended fish (a flasher will improve your crappie fishing 200% because you'll see fish that you can't catch when fishing the bottom 3'). Crappie also prefer low light most of the time, i.e., morning and evening and most especially, dark. If you really want some slabs, go to lakes that are known to have many of them. Often, most crappie anglers local to many of the PA lakes that I frequent don't even show up at the lake until 4 p.m. or so. I fish as many hours as possible and target species that I know are most active. All panfish in the morning, bluegills and perch during the day, all panfish at dusk, and crappie at dark. Often while targeting one type of fish you may pick up others too. Get a bright lantern to bring out on the ice, the light attracts bait and the crappie seem to find you. I've often thought about investing in one of those underwater lights too, but have yet to do that.
Good jigs for crappie (get glow colors - glow red, glow chartreuse, glow blue, plain ol' glow):
Demon, size 8 or 10 with maggots or waxworms.
size 6 Fat Boy or Genz Worm with a small or extra small minnow
size 8 or 10 Fat Boy or Genz Worm with maggots or waxworms
soft plastics, like the ratso or shrimpo, get both large and small sizes. If you can find the plastic tails for these lures, they work well on 1/80 oz. jigheads and all other ice jigs too, many times better than maggots or waxies. Get the glow colors in these too.
Other colors work good too, like black, orange, chartreuse, firetiger, gold, silver...but glow seems to be best.
Good luck!!!