Match the hatch, clousers, sandeels, peanut bunker.... Tie flies similar to these to start. Find estuaries, bolder fields, flats... areas that you know hold fish. I started with intermediate line, you can cast poppers and other flies.
"Always two there are, no more, no less: a master and an apprentice." >> Yoda
Casting (IMO) fresh and salt are two different beasts. I can fish in a river pretty darn well, but when you couple the action of the surf and the high wind you encounter when fishing the salt... It's a learning curve for sure!
Find a dock that has big lights on it during summer nights and try heavily weighted white flies.