Judging by the OP's join date, and post count - I would have to assume he is new to the hobby. If not to the hobby, then at least new to RR - so to you I say - WELCOME!
There are several resources out there on what you can listen to in Suffolk County. As a start, what are your listening interests? Some enjoy just listening to Police and Fire. Ok - so you have the county trunk system and about 300 conventional frequencies to put into your scanner.
Remember, your on LONG ISLAND.....surrounded by water! Try listening to the US Coast Guard and the VHF Marine Channels. We have AIRPORTS... put the common aviation frequencies (try 123.45 AM) into your scanner and your closest Airport.
What else is out there?? Try NY State Police, Long Island Rail Road, Amateur Radio, FRS, GMRS, search the business bands. We live in one of the most RF Congested Environments so there is PLENTY of things to listen to.
Enjoy scanning on Long Island, there is plenty here to hear!