A few dock shooting tips:
1) "Light" not "UltraLight" action. UL is too whispy. 4'5" - 6' length. I wouldn't recommend anything longer when you're just learning.
2) Spinning reel or underspin. I actually prefer a little larger reel. Really small ones wind the line up in a tight loop and those loops are detrimental to a good hook set when you're letting the bait free fall. A bigger reel tends to release line that's less twisted.
3) 4-8lb hi vis line. Lighter the better. As the bait falls, you will see your line "twitch" when you get a bite. You don't want to close the bail and tighten the line too early because it will pull the bait back toward you. You want that jig to fall straight down as far back under there as possible. Then you can work it back toward you, and you'll still be watching your line. When done right, you'll see the bite before you feel the bite more often than not.
4) 1/16 - 1/32oz jig head with a bulbous shaped plastic body. The more rounded shaped body allows the bait to "skip" across the water and get further back. Most of the plastic jig makers have a model that fits this. Don't bother with painted heads until you get good at shooting. That paint will likely get knocked off the first 50 tries, because 47 of those will hit the dock.
5) Hold the head of the jig with the hook away from you. Seems like a trivial point, but you don't want to find out why.
6) Keep the backbone of the rod (butt to first eye) parallel to the water. Let out about half the length of the rod in line. Pull the jig back so that the line from the tip to the jig is also parallel to the water. This helps to keep the trajectory of your jig flat and parallel with the water. Practice in the driveway shooting under a chair before you go.
7) Look for docks with at least 6-7'+ depth at the outside edge of the dock. The deeper the better. Shallow ones will hold a few, but usually smaller fish. Bigger docks and ones with lots of poles are best. It's all about shade.
8) Shoot into the darkest (hardest to get to) part of the dock. That's usually where they'll be.
9) If you get bit, keep working on getting in that SAME spot.
This is by far my favorite way to catch crappie! It's a challenge, but when you get into them it can be a blast!
Good Luck!
EW