Assuming that you have already taken the basic precautionary security measures of changing the default SSID on your Access Points/Routers, disabling SSID broadcast on your Access Points/Routers, and using a stronger password on your Access Point/Routers, the next thing you should be worried about it making sure that your wireless clients (computers equipped with wireless adapters, and wifi-enabled PDAs and smart phones, etc.) are not accidentally connecting into untrusted/unknown wireless networks.

A sneaky trick often applied by wireless-bandits is to show up in close proximity of your wireless LAN with a rogue Access Point that allows connections from anyone. To increase the chances of someone "accidentally" joining their rogue wireless honeypots, they usually configure their rogue APs to use and broadcast factory-default SSIDs. For example, if you have a D-Link WiFi card in your laptop computer and you happen to be running your wireless uplink (wifi card) in default (insecure) mode, your laptop may just miraculously discover someone else's rogue AP in the nearby area if it is found to be announcing its presence by broadcasting an SSID that may be known (e.g. "default" -DLink's factory-default SSID) to your DLink card. Even though these kinds of "unanticipated" wifi associations frequently, often the persons taking such an unauthorized (but highly risky) ride on someone else's wireless network do not even have the slightest suspicion that they are potentially exposing their private data by letting it pass through unknown/ untrusted rogue access points.

From security standpoint, there is nothing worse than joining someone else's unknown/untrusted WLAN. There is no way to tell if the persons whose rogue IP you are linking up to are running a network sniffer. They could very well be collecting all your traffic data -especially if you are using plain-text authentication for accessing your email and other personal accounts.

The possibilities that you may be unknowingly connecting to someone else’s rogue network are real -it can happen anywhere: in your home, your favorite cafe, at the airport or in and around your place of work.

The only way to reduce your changes of unknowingly routing all your online activities through a rogue/unknown network is to configure your wireless adapter to associate with only a predefined/known access points and wireless gateways. You can do so by entering SSIDs of a known set of "allowed" or "trusted" APs, or by enabling MAC Address filtering or IP address based filtering, and by making use of a share-key for encrypting all traffic (not just for your authentication packets, but also for your data) between your system and your wireless uplink device such as an AP or a Wireless Router.