...a 4oz rod could be anything from a five weight to an eight weight--what is the line rating of the rod? It matters--some sinktips are heavy, and require backbone to cast...not to mention land fish. I saw two sorry anglers who broke their rods on chum in the Stilly last weekend...

...as to practicing on lakes, it might be a good idea if you're unfamiliar with basic fly casting techniques, but sailing a heavy marabou fly out on the end of a type VI sinktip in current is a special kind of casting all in itself, and nothing but doing it will help you along. That said, search this bulletin board for the "Any fly fishers out there" post by DanO (on 11/3/00)--recommends excellent material to get you started.

...and above all, sharp hooks...