Mississipi River Help

Can somebody offer some advice?
I just started fishing the Mississippi River near Vicksburg,Ms on the Louisiana side.My 1st trip was this past Saturday-I fish from the bank(no boat,yet). I was able to catch about a 15lb flatty in roughly 2 hours of fishing on a live shad fished on bottom. I had a problem catching enough bait and didn't even get a bite on some frozen shad and buffalo. What else would be good to use-I know live or cut bream is a good bait to use. What would be a good rig for the river? And is it best to cast out as far as possible from the bank,fish along or close to the bank? I usually bottom-fish,but I have a couple of really big floats and I'm considering trying that-I'm hesitating because of all that current. I'm trying for flats,blues,channels-whatever.My ultimate goal is to tangle with some 40lb+ fish-mainly for pictures and just the thrill of it. Any tips/help would be greatly appreciated.