Dark colors for stained water. Light colors for clear. Over the years my favorite jig color is solid yellow. It works in most all conditions for me. Chartruse is a good color. The fish seem to see it well. I think the main thing is presentation. Bump'em on the nose and they will strike. Crappie are lazy fish I think so they want to eat the most with the least amount of energy so don't be scared to use a 2 inch tube or jig.
Casting Jigs.
Spring fishing calls for the jig & float(slip bobber with jig from 1'-5' below) because the fish are shallow(1'-6' to spawn). But don't forget they still stay in staging areas and go back and forth to spawning grounds. You need to get it down to that 8'-12' range. Always tip that jig with a minnow on slower days. I start out with one and leave it off after I catch a few. If I keep catching fish I leave it off.
I have never used much attractant but Jerry Blake uses cod liver oil on his jigs and if he does it it works.When I caught my biggest crappie cod liver oil and a minnow were on the jig.
Trolling jigs
I started trolling for crappie about the time I found this board last year. I still have so much to learn. One thing I catch fish on is the roadrunner heads and beatle spin with a jig or tube. The roadrunner types work best for me this month.