Speck (or sea reout) and redfish are plentiful. if in charleston a good source of info is charleston anglers (
www.charlestonanglers.com) or stop in to one of their two stores for a chat. if interested in a guide see if
Richard Stuhr is available or one of the guides through above.
the best times i have had are wading the grass flats but you need a boat/guide to get there.
if you are with a guide no license is necessary but even in salt a SC license is a must if you are alone--you can get this online (google south carolina fishing license)
have used relatively small (4-8)crab and shrimp patterns on the flats with a 7 or 9 wt rod
good luck--a beautiful place to fish