For fluke best bet is either on the south side in 50-70 feet of water off the radar tower or in the north rips. You'll have no trouble finding the fluke fleet in either spot. For sea bass best bets are either frisbees of the west grounds off block island. You'll find both marked on the fishing charts. for stripers great eastern or pollack rip. Blues can be had all around the point, just look for the bords and busting fish, little tunny and bonito are often mixed in with the blues.
What M/M said is true but if you don't want to fish with the fleet go west off the town, or Heather hills state park. The 1/2 day boats don't go that far.
Don't get me wrong the places M/M had stated will produce but your chances of getting some bigger fish might be a little west.
Bottom line is daily reports from people at the dock where you are.
I don't have my loran book handy, but if you run west down the beach, where the cliffs stop you'll see a big white house on the beach, frisbees is offshore of that. You'll know you're there when you see all the lobster pots.