I've had great luck shrimping around Sidney off the James Island pier and Tulista boat ramp in late fall to Christmas as the shrimp get shallow to spawn. Two effective methods:
1) Butterfly net and headlamp at night to see them attached to the pilings. Scoop them with the net.
2) Get an old bike tire and take the spokes out. Sew in a burlap sack and use some wire to make a Bait holder (or use a readily available crab trap Bait holder). Attach 50' rope to it (Make sure the when you raise it it stays flat). Drop to bottom with a punctured oyster or sardine can attached for about 20 minutes, then pull up. Repeat.
Good luck!