I'm guessing you are shore fishing so I will approach it from that method. Your best bet for Crappie is to fish docks fixed and floating, if your on a dock and can see timber sticking up would also be good place to sight in on if you can cast the light weight jig that far. (I dont believe in float bobber casting with jigs)
The best docks and piers will have abundant forage, a considerable amount of shade and protection, and be near deep water. The more comfort provided for crappie and their forage, the better your fishing chances will be. Stay away from newer docks as they will have chemicals and stuff on the timber and wood and until this dissolves the fish will stay away. The older docks have algae growing on them, which attracts baitfish, and that attracts the crappie.
Probably the most important thing is shade and protection. Docks are best when its sunny and hot. Clouds tend to make the cover less important and causes fish to scatter. The bright sun penetration pushes crappie into the most shaded area under the docks, and it?s not unusual when crappie will be on one side of the dock in the morning, and then on the other side later in the day. The wooden docks just a foot or so above the water is ideal. The posts and cross-members also provides shade and protection for crappie. Sunken trees, brush, stakes and other man-made structures can often be found directly below or at the end of docks. Many dock owners do this to establish a holding area for crappie and also to hold a larger concentration of fish.
Deeper water, at least nearby, is another key ingredient. Shallow docks may produce during certain seasons, but deep water structures will hold crappie year-round. Other than the spawning season, the water depth beneath or at the end of a dock should be at least 6 feet to attract crappie.
Always try to fish on the shady side of the dock or post, especially if the water is clear. As the sun moves across the sky, the crappie will move with the shade to the other side of the dock, and you should too.
Keep in mind though, the crappie may be on the sunny side of the dock for a number of reasons. If the water is dingy, and there?s a brushpile in deeper water, they will hover in and around the cover. Also, in early Spring and late Fall when the water is cold, they will be on the sunny side and near the surface trying to get warm.
The best technique with the jigs you described is to use a light weight rod (crappie rod) drop your jig along or under the dock and just jig it slowly. If casting at timber jig up and only reel as it falls and keep that up. I think scent is very important for crappie too, so by some kind of scent spray or liguid to kill your scent on the jig.
You will probably catch a few small bass following this technique as well but its a good distraction.