Fishing a small jig under a slip bobber or a fixed float is effective and it is deadly on Crappies. I prefer the sliding float method as it allows me to cast the bait rather than move the boat. The float bobs up and down with the water movement and provides action to the jig. The technique doesn't require any extra movement and the wave movement is all you need. Crappie feed up, watch for your bobber to lay over signaling a bite.
In fairly clear water, a smaller jig will be better. My favorite is the “Electricity” jig that I make. This is my setup.