Gambler Heavy Cover Southern Swim Jig
First and foremost, this is my favorite swim jig. It has a big, beefy hook which is what you want for swimming a jig. I use a swim jig year around because they're so versatile and this particular swim jig has been my money bait. Everything about it is top notch.
Swim jigs excel in/around aquatic vegetation, but I catch fish around timber, docks, and even open water as well.
Starting out, just keep it simple. Take a shad color, a green pumpkin color, and black/blue color and fish those under the appropriate times. A shad color works best during the Summer and Fall, while the green pumpkin color and black/blue color work best during the Spring and Winter. when imitating a shad or bluegill, match the trailer to jig color; I either use a paddletail swimbait or some sort of swimming craw. When the bass start spawning, all they way until the bluegill are done spawning is when you MUST imitate a bluegill. That's one of the most fun and vicious bites you can ask for. They absolutely hate a bluegill colored swim jig rolling on by them.
I mostly fish a swim jig in water less than 8 feet, but if fish are chasing shad over deep water I'll bump up a size and count it down to them. That's a technique that I don't see a lot of anglers do but it's very effective when they don't want a deep diving crankbait.
There are lots of things that swim jigs are good for, but around shallow cover is the most effective.