Crankbaits, especially deep diving crankbaits.

I've caught a few but I don't throw it often or with any confidence. I've mainly fished them along the river's ledge on Guntersville. Where do they shine? What conditions make them a good choice? It is certainly my least favorite way to try and fish, but if I had more success/confidence, I'm sure I would use them more. I guess it is like anything, tie on one and only fish it for a while.