Salisbury is not really a dangerous city. You don't need to constantly look over your shoulder or be suspicious of everyone you see, but you should definitely keep your eyes open. As a traveler, you can always be pointed out and targeted. You should try to blend in in every way possible. You should definitely not walk around with your camera slung around your neck. This is an obvious move that a tourist would make. Just keep the camera in your pocket and pull it out when the time is right. If you are eating at a cafe or somewhere outdoors, you should never just leave your wallet or any other valuables on the table. Any thief or pick pocketer can come up and take it without you noticing. Of course, in Salisbury, this isn't really a problem to begin with, but you should still exercise caution. Salisbury gets a large amount of tourists, many of which are international tourists. Because of its close proximity to Stonehenge, there is a constant influx of people coming and going. This means that the locals are used to travelers, so they will essentially assume you're a tourist if you are hitting up all of the popular spots, so you don't need to worry about assimilating as much. If you ever get in trouble you can go to the Salisbury Police Department, and if it is very serious you can go to the American Consulate.