This is a topic I still need help with myself, but I'll add limiting the amount of time you spend in one spot.
If I'm using stink/dip bait, fifteen minutes without a bite is my limit. Using other baits, thirty minutes. I especially enforce this limit on myself during April and May, June too if this cool weather holds.
On big lakes, I think power generation at the dam has a big influence on the daytime bite. One summer on Pickwick, we put out 35 noodles early in the morning spread over a variety of areas. We worked them for three or four hours and only caught one or two fish. Middle of the day, it was like someone flipped a switch, and we started catching fish. At the same time, I noticed that the ones we placed in creeks and coves were moving out toward open water. I assume power generation at the dam was creating current explaining our improved luck and the movement of our noodles.
Fishing noodles like that is a great way to learn a lot about catfish locations. General rules of thumb for location, in the spring look for them to be shallow in creeks/coves or near bluffs/rocks. Summer look for them deep near channels and bluffs.
Big rains can also be a God send to the catfish fishing. If I were in the Memphis area, I'd be after them tomorrow. Look for creeks and wet weather streams dumping storm water into the lake. The best day I ever had was on Pickwick after two straight days of rain brought on by a tropical storm. We caught a cooler full on 35 noodles in three runs, that is bait/drop and when the last one's out start collecting your fish.
If you're taking a kid, check out TWRA's family fishing lakes. They are usually well-stocked with catfish.
