Up here in the ice belt (Nebraska), water temp and length of day seem to dictate what the crappies do. Until the water warms into the upper 50s to low 60s, I target deep brush and timber as a rule. That's where I find the greatest concentrations of fish and can take them vertical jigging with a small tube or on a minnow under a slip float.
Once the fish move shallow to spawn I go exclusively artificial, preferring a tube under a slip float, or casting Beetle Spins and Roadrunners. I like to swim a Panfish Assassin too, just outside the the shallow spawning areas to pick up fish still staging a little deeper.
Love the 4# hot yellow crappie line from BPS for most of my panfishing, on light spinning reels. The fish don't seem to mind the bright line one bit, and most importantly, I can easily see it under any light conditions.
Frank