Here are some suggestions:
Shrimp -Live shrimp are, by far, the most popular live baits, and are generally considered the best all-around bait because they are readily available, are fairly easy to keep alive and just about all fish love them. They are sometimes referred to as "trout candy."
Shrimp are the primary diet of school trout, but larger trouts' diet is made up of mostly finfish. Other popular species such as redfish, back drum, sheepshead, flounder, channel mullet and white trout will also readily eat shrimp.
Croakers - Croakers are probably the second-most popular live bait used, and are one of the best baits for trophy speckled trout. They are more difficult to find at bait shops, and are not as easy to keep alive as shrimp.
They can be caught using small hooks baited with small pieces of shrimp and sinkers on the bottom.
The best size croaker is between 3 and 6 inches long.
Menhaden (aka pogies) - Menhaden gather in very large schools during the warm months all along the coast, and are a favorite food of speckled trout and redfish.
These are delicate fish and must be handled carefully. A supply of outside water in the livewell is required.
You generally will not find these in bait shops, but they can be easily caught with a cast net, once you locate a school.
Finger mullet - Schools of mullet can be found all along the coast in bays and lakes. Finger mullets are those that are between 4 and 6 inches long, and are great baita for big trout and redfish.
You will need a cast net to catch these. Finger mullets are fairly hardy and easy to keep alive.