I've done some catfishing and never caught nothing huge, but i have never had trouble catching numbers. i like cutbait, as fresh and oily as possible - we have herring that run up our river from the ocean, and they are really good, but are only seasonal. I will usually load up on the herring in the spring and freeze enough for the rest of the season. Cut bait caught the same day though is always better than something frozen then thawed. I like to cut up herring into cross sections as they are a smaller fish...for larger fish like big shad, i will fillet them leaving the skin and ribs on a fillet, and then use 3" x 2" strips...but experiment with bait size, sometimes they like bigger, and sometimes smaller
I use 30lb fireline for main line, and then i like a soft braid for a leader, like tip up dacron. I think catfish can feel the hard mono and it turns them off versus soft braid.
for hooks i like eagle claw L042 in size 2 or 2/0.
in terms of rigs, for drifting and really snaggy bottoms i like to use a dropper at the leader and crimp some big split shot on there. If the bottom isnt snaggy and current isnt a great issue, i will use a slip sinker rig with an egg sinker, and a bass casting sinker when current is an issue. I will also try 3-way rigs (like in TH's illustration above) if it seems they want the bait off the bottom or are active.
oh yeah, i am targeting white and channel cats.
i also dont like to let the fish take much slack line...i just set it when they bite.
there is an excellent book on catfish in the in-fisherman series.