How do you prepare and set up for flounder fishing?

This depends on your local fishing regulations. A typical rig uses a three-way swivel. One swivel is tied to your main line. The second goes to a weight, typically 18" to 24". The third swivel goes to a piece of fluorocarbon or monofilament fishing line, longer than your line to the weight, with a hook sized to match your local live bait. A trap hook, usually a smaller treble, is connected to the third swivel and pinned into the rear of the bait. If you use an artificial bait, leave off the trap hook.