Make sure to turn off file sharing and network discovery

These both put your files and system at risk for being opened by anyone on the wireless network, not just hackers. In Windows, these options can be found under Control Panel > Network and Internet > Network and Sharing Center. In Mac OS X, they are under System Preferences > Sharing. If you are within range of public wireless networks but don t need to be online, turn off your wireless capabilities altogether. On some devices, there is simply an on/off switch; on others, you will need to configure this yourself (ex. on a Mac, click the Wi Fi icon and turn off AirPort).