Salem is a small city, but it is still an urban environment. Within Salem you will find corners of quaint New England; intersections of hustle, bustle, and traffic; and neighborhoods of hip boutiques and unique dining. In the mix are, of course, all of Salem's unique attractions and extraordinary museums.
All this is to say you should wear your walking shoes.
If you're not a big fan of getting from destination A to destination B (and on to C, D, and E) on foot, there are options. Salem is a two-trolley town. Cityview Trolley (silver) and Salem Trolley (red) are equally willing and able to provide both a one-hour narrated overview of Salem and then provide on-and-off shuttle service to help you connect sites. Both trolley companies service the Salem Ferry.
A slightly greener, and perhaps more colorful in all ways, mode of transportation is via pedicab. Salem is also a two-pedicab company town. Historic Salem Pedicab Tours and Salem Pedicabs will gladly take you wherever you need to go for free - the pedicabs operate for tips only. Historic Salem Pedicab Tours also offers pre-arranged historic tours of Salem's different neighborhoods and concierge services, as well as point-to-point transportation. Pedicabs also service the Salem Ferry and can be hailed around the streets of Salem.
If you're driving, park in one of the two Salem garages and leave your car for the day. If you travel by train or ferry, rest assured the trolleys and pedicabs can get you where you want to do, should your feet get weary!