Burlington International Airport
(http://www.btv.aero/) is not too far out from South Hero. You can simply book a flight into Burlington, rent a car and then drive into South Hero by using I-89 and Route 2.
By car
If coming from the South and Southwest areas of the U.S., Route I-87 will take you up the east side of New York which parallels the West side of Vermont and Lake Champlain. If not taking the ferry, you can drive all the way up to the last exit on I-87 to Rouse's Point, which will take you across a bridge that goes over Lake Champlain, then you would continue down the Islands on Route 2 southward where you will start to see signs for South Hero. If coming from areas in Southern New England and anywhere in New England, Routes 89, 91 and 93 will get you to the Burlington area which from there you will be able to get to South Hero by following signs for Lake Champlain Islands on I-89.
Lake Champlain Ferries
(http://www.ferries.com/). There are three exits off of I-87 that will get you to ferry ports that will take you to the Vermont mainland. These three ports are located in Essex, NY, Port Kent, NY, and Plattsburgh, NY and take you to Charlotte, VT, Burlington, VT, and Grand Isle, VT, respectively. The one that will take you right to South Hero is the port in Plattsburgh. However, if you take the other ferries to Vermont you will be able to get to South Hero by taking Route 2 North.