Live bream for ops
Cut bait - skipjack is great, pogies good too
Market shrimp is real good too on the MS River
Have heard the soap thing, but I saw a show where commercial fisherman were using plain ol Ivory soap. I don't think just any soap will work, I wouldn't go out there with Irish Spring

They used this because it was cheap and stayed on the hook. The other bait they were using for trotlines was .....those big marshmallows