Without getting stupid we suggest the following:

Stay up-to-date with patches and updates

As with any computing device, your router has special operating software called firmware. Most commercial companies will release patches or updates to that firmware. While these are not frequent, they can often fix security vulnerabilities in the hardware. You can likely check for updates in the router administration area.

Another effective practice is to ensure all updates and patches are applied to the devices connected to the network. Gaining control of one device on the network, especially an older, forgotten machine, gives an attacker a foothold to move on to other, more valuable targets. If you're not using a computer or other device, turn it off, or at least disconnect it from the Internet, if possible.

Choose a strong administrator password

Most routers require an administrator password to access the setup and configuration settings. However, the default passwords for these routers are generally weak, and some have none at all.

You should change the default password to something strong. Once you have set up your wireless network, you will probably not need to use this password frequently, so you can use a very strong password without worrying about the difficulty of typing it in. If you do lose the password, you will have to reset the router to factory settings and set up your network again.

Disable remote administration

Many wireless networking routers offer the ability to allow administration of the router remotely, from anywhere on the Internet. Unless you require remote administration and are very familiar with WLAN administration and security, it's a good idea to disable this feature. Otherwise, anyone connected to the Internet could conceivably gain administrative access to your router and network.

Encryption

For best security, you should enable or set an encryption password. All Wi-Fi equipment will support a form of encryption; you should choose the type that is most secure and will work across all the devices you need to connect.

If possible, use WPA2 (Wi-Fi Protected Access). If you are using a home wireless network, you should choose WPA2 Personal. Some older devices may be unable to connect to a WPA2 network; in these cases, use WPA.

There are still some old devices that may not even be able to connect to a WPA network, and will require WEP (Wired Equivalency Privacy). While WEP encryption is slightly better than none at all, WEP is not considered secure, and you should avoid using it. If you do need to use WEP encryption, be sure to choose a very strong password, and change it relatively frequently.

Change your default SSID

Your SSID (Service Set Identifier) is the name of your network. Pick something that is personally identifiable, but not externally recognizable.

MAC address filtering

This won’t stop anybody but your lame neighbor. Not worth the effort.