Depending how you  are coming into the island, (by cruise, private yacht, by plane) it is easy either way.

Princess Juliana International Airport
The new, state of the art airport terminal, is yet to be handed over to the public. It is an impressive building. We'll see how easier it will make for visitors. Please come back for updates. As for now, when you reach at this airport, you'll be standing in line to meet the immigration officer at the booths and once passed, you entered the baggage conveyor room. Everything is in short distance. Once you got your baggage, you step out, and on the left you'll see about 8 car rental booths. If you have not booked a car rental in advance, here is where you can wheel and deal for the best rate. If someone is picking you up, just walk out, and surely you'll see someone with your name on a placard, or the taxi drivers are waiting for you. If you are in transit  to visit another surrounding island like Saba for instance, it depends if you have booked a connecting flight with Winair or are going by boat. The boat to Saba leaves at Pelican Marina early morning and at noon. St. Barths ferry leaves in Marigot water front or Dock Maarten Marina in Pointe Blanche.

Grand Case Airport
This is a small airport on the French (Northern side) of the island. This airport is mainly for interisland flights with small aircraft like going or coming from St. Barths, Anguilla, St. Kitts etc. They also just renewed that airport with a nice parking lot. On that airport there is also a flight training school.

Cruise Ship Port
This is located in Pointe Blanche. Once you arrive by cruise, you have the option how to move. You can either choose to visit the island by foot (Philipsburg is a 20 minute walk away), by taxi, tourbus, or taking a tender to Philipsburg

Various Marinas
If you happen to be one of the lucky few that come in a private yacht, there are many marinas on the island to accomodate you. More will come on this on this site.