I fish almost exclusively saltwater. I usually use live shrimp, fresh dead shrimp, or mud minnows for bait when I am fishing from the kayak. I also throw a lot of grubs. Some of my friends will use finger mullet, menhden, fiddler crabs, and/or blue crabs.
When I surf, pier, or shore fish, I might also use cut mullet, cut pinfish, or squid (not as often)..
In Mount Pleasant, you could stop in at Haddrells Point or Charleston Angler and they guys there can help you with bait or fishing spots. In my experience, salt water fishermen are very eager to help someone who is wanting to get started.
You might also want to check out the website for the East Cooper Fishing Club
, eastcooperfishing.net. Their next meeting is on Monday night (first Monday of every month. The first two or three meetings are free and Dues are $40 per year, January through January. The big part of the club is the forums
. A limited part of the forums are open to non-members.