When getting around Grenada you can use a diverse array of means of transportation. You can drive, take a taxi or a water taxi, board the  ferry, hire a motor boat, jump on a bus, take a plane or just walk. It depends on where you go, your desire for diversity and the time that you have to get where you are heading.

To get around St. George, your best option is to walk. The city is beatutiful and if you have the time you can admire the historical sites (be sure to grab a walking tour guide from the Tourism Office at Burns Point). You can take a bus (the service is frequent and inexpensive - $2 EC-) or a taxi. A good idea is to hire a taxi to tour the island, the personnel at the front desk of your hotel can help you with the arrangements. There are also mini vans that can take you in a tour trough the city and to the rest of the island.

The mini-bus system is a fantastic way to travel if you want to be closer to the locals. There's almost no schedule and you / they will wave or honk wherever you need them. Cost is extremely cheap (2EC to ~ 5EC) and even fun considering the way they drive (especially around the hills). You may need to learn a few routes depending where you go on the island, but all routes starts and ends at the bus terminal in St. George. Be specific as to where you want to go and the drivers will usually get you there as close as possible on the typical route. If there is no other passenger and they go off the main roads to your destination the cost is usually doubled.

But, to get around the island, your best choice is to rent a car. Keep in mind that driving in Grenada is on the left side. A downside is that during the rainy season that goes from June to November, roads deteriorate a lot and the government cannot repair them promptly. So,  pay extra attention to the road conditions plus to minivan drivers (there are lots of this kind of vehicles specially outside St. George) who don't drive safely. But, don't panic, driving shouldn't be a problem. Remember to purchase your temporary driver's license: the rental company will help you with the processing.

If you want to go to any of Grenada's islands (Carriacou and Petite Martinique) you can either take a ferry (there is a daily service to the islands) or you can fly and be there in about half an hour.