The most important thing at first is to find and identify them - which is very difficult to do. Termites often do their damage well out of site, as a safety mechanism against predators. So look for mud tubes at first. Mud tubes are what most species of termites use to travel.
If you do find their damage, most people mistake it for carpenter ant damage. But termite tunnels usually have "frass" packed into their tunnels, whereas carpenter ants keep their tunnels very clean. See the picture below for an example of what termite damage looks like. Questions? Contact me!