When the water is very clear, use a single lure and switch the egg sinker for a split shot to help keep from spooking the fish.  The main thing to remember is that trying different rigs is a good way to find what works for you, but once you have hit on a winning combination, switch all, or most of your rigs for what is working best.

If you are finding crappie in the heavier cover areas such as brush piles, just set up so you tickle the tops of the brush.  If your electronics show that there are fish responding to you there, switch over to a single rod and jig vertically with about a 10' crappie pole and a good weedless rig such as a wireguard type.

Summertime is the prime time for spider rigging for crappie, because they seem to hold quite a bit deeper during the hot months.  They seem to keep to the channel edges rather than holding tightly to the cover as they would any other time.  Because the crappie are not holding tightly, you can fish a broader areas along a breakline rather than concentrating on the cover areas so much.  

There are many ways to bait for crappie, but spider rigging is a good one that is very popular.  Try it, and see if it works well for you!

To get the full "Techniques For Baiting Crappie" article you'll need to download it here.