Fish Gal,
to start out with, use an airport close to your home. You'll fly into Belize City (BZE), then take a hop to San Pedro Town (SPR). If you're spending any time in Belize City you can also use the Municipal strip (TZA), which is closer to downtown. That makes it nicer, as well as cheaper, if you're connecting to a tour out of the Marine Terminal.
  You can see a little about my first trip to San Pedro Town via Maya Air's Cessna 172
here.
    Dan