Nassau County is generally divided into North Shore and South Shore. The North Shore is known for its hilly roads and rocky beaches. In comparison, the South Shore of the County is flat and contains sandy beaches. The Long Island Sound splits the North Shore of Nassau County from Connecticut while the South Shore leads to the Atlantic Ocean. As a whole, the county spans 453 square miles. 
Nassau County is the second largest county by square mile on Long Island (Suffolk being the largest by far). It is sandwiched between Suffolk County and Queens County. The County Seat is in Mineola. Nassau County also has several beaches, including Jones Beach and Long Beach. You can also visit the downtown areas of each village. There are typically many shops and sometimes even restaurants in those areas.
English is the main language. Hempstead, Uniondale, New Cassel, Westbury and Freeport have large Spanish-speaking populations.
Take the Long Island Railroad, Long Island Bus, or drive in via the Long Island Expressway, Northern State Parkway, Southern State Parkway, or Sunrise Highway.
Getting around is very easy by car, especially with the presence of the Long Island Expressway (commonly referred to as the LIE in the area) and several other parkways.
All American Hamburger Drive-In in Massapequa is a vintage, 1950's-style burger joint.
Nassau County is in general a safe place to visit. As anywhere, just use basic common sense; this is the average suburban county. Crimes, if any, usually occur in Hempstead, Freeport, Roosevelt, Uniondale, New Cassel/Westbury and Elmont. The Island Trees/Plainedge area of Levittown has seen an increase in crime lately, as well as the western part of Hicksville south of Cantiague Park. Gang violence is rampant in New Cassel, Hempstead, Uniondale, Roosevelt and Freeport. The only safe areas of Hempstead are west of Cathedral Ave, north of Hempstead Tpke and east of Westbury Rd, north of Hempstead Tpke. Uniondale and Roosevelt are safe in the daylight, but be extra careful at night. New Cassel is relatively safe during the day but very dangerous at night. Freeport south of Sunrise Hwy is very safe.