Here is a secret that my wife's grandfather showed me that really works.
Take a crappie jig and one of those small hollow tube jigs and take a small piece of cotton and shove it up inside of the tube. Place the jig hook into the tub and dip it into your favorite crappie scent. The cotton soaks up the scent and holds it much longer then if there wasn't any cotton. This is deadly on the crappie/bluegills here in my neck of the woods.