Extra Security Options
Of course, it's a little boring to just tell you to use strong encryption and call it a day. There are a variety of extra steps that are recommended to better secure your network. Let's go over a few of these wireless network security issues.
Not Broadcasting Your SSID - Your SSID refers to the name of the network. It's what shows up when you look for networks to connect to. A lot of people (even a few on Bright Hub) suggest that you turn off SSID broadcasting to help hide your network from hackers and make it "invisible." Note that not broadcasting your SSID is roughly the same as throwing a tarp over your car. It's not going to hurt anything as long as you don't mind pulling the tarp off when you want to drive (or in this case, setting up all connected computers to automatically detect and connect), but it's not really hidden. The tools that are usually used for wireless network hacking are all able to automatically reveal "invisible" SSIDs. It will do absolutely nothing to protect it from anyone using anything more complicated than the Windows wireless connection process. It's not a bad thing to do for a personal network and can hide your network from bored neighbors. Note that businesses will see their IT department driven insane after a few days of "how do I connect?"
MAC Filtering - MAC filtering is also recommended and I personally like it. Each computer has a unique MAC address and you can configure your router to only allow a small list of MAC addresses. It's a good idea overall, but it's about as useful as hiding your SSID. A serious hacker knows how to spoof their MAC address to an allowed one. If they have basic access to the network, then they can just look for connected devices (since they are obviously trusted) and then spoof their own MAC address as one of those. It's covered in this list of all possible Wireless Network Attacks. This is closer to locking your car doors. Someone could just pick the lock or break a window, but you're making them take the extra step and preventing them from just opening up your door.
Strong Router Password - This might not directly protect your network, but it's just a good idea. Do not leave your router on with the default password. There's a big list of those and it's the first thing that a wireless network hacker will check. Go ahead and make the admin password something strong. On that note, make sure that remote administration for the router is turned off. You shouldn't ever really need to use that and it only allows other people to crack the router password and change your settings instead of cracking the encryption.
Educate Your Employees - The human link is always the weakest. Make sure that your employees know how to stay safe online and that they don't broadcast company info to the world.