Chumming is a very effective way of attracting fish into the vicinity of a baited hook, and of delaying the passage of passing fish so that you can place baits in front of them. It can also be used to encourage fish to feed when they otherwise might not. The secret lies in using the right amounts, appropriate to the species your after, utilizing the prevailing conditions and not feeding them to the point that they have lost their appetite for your baits. The idea is that the chum will produce a chum "slick" that will reach several hundred yards. Baitfish are drawn to the slick and gamefish will soon follow both as a result of the slick and the baitfish.
An excellent source for chum making material is your friendly local shrimper. Usually for a few bucks you can drop off a cooler a few days before you plan to fish and he'll load your cooler up with by-catch from his nets. Fix you up a bag of whole fish for cut-baiting, then take the rest and chop and mash it. Freeze it in 5 gallon buckets and it'll be ready when you are. I usually hang a milk crate off the back of the boat just low enough to the water where the waves can lap at it to melt and disperse the frozen chum mixture.
One thing to watch for while fishing, is the opportunity to tag up with a Shrimp Boat soon after pulling up his nets. Shrimp Boats can be found all along the coast line, on their way in or as they anchor up for the day after shrimping all night. They'll wash down their decks and pitch all of their "by-catch" over the side. The by-catch, which consists of all the small fish caught in the shrimpers nets while dragging, will make a substantial chum line. Often, if they have not retired for the day, a shrimper will sell or trade several buckets of by-catch for you to use as chum, and lots of people buy or trade with them. As they prepare to rest for the day and wash the decks down, they create a chum line of their own that draws fish. Just tie off, anchor up, or drift along behind them.
There are all kinds of Chum Grinders, Chum Bags, and Chum Baskets on the market. You can also make chum on the fly with a specialized grinder that fits into a convenient rod holder on your boat. Search through your local garage sales and pick up a cheap meat grinder to make your chum with before plunking down the cash for a specialized system. Chumming maybe too messy and troublesome for you.
It does involve some extra work but, give it a chance. You'll be amazed at the fishing action when everything falls into place and a feeding frenzy gets going.