Get into your Router control panel
You will need to type in your IP address, it's usually 192.168.0.1 and type in the log in information which usually located somewhere on your router.
I suggest you take out your handy router manual to speed up the process.
Create a new administrator password
Always a good first step, once you find it, change the password to something you can remember in case you will have to reconfigure your network.
Don't make the password obvious like 12345.
Turn on encryption
You will want to turn on the encryption. Use WPA if all devices on your network support it, Otherwise use 128-bit WEP. Type in the key you'd like to have as your password.
It is often a number but in the router control panel you can change it to whatever you want it to be. Remember the password you're using so you can type the password whenever you need to reconnect to the network.
Make sure you remember it, and make it random so no one could guess it.
Change the name of the network
Nothing says "weak wifi protection" like the default SSID (network name) like Linksys or Netgear. Change it to something, anything. It will give the impression of a powerfully protected network.
Turn off SSID broadcasting
When you scan for networks in Windows, you get a nice list of networks. If you don't want your network to show up in this list, turn off SSID broadcasting. It can be annoying since you will have to type in the network
name manually afterwards.
Enable MAC filter
MAC is a feature that lets only chosen computers by you to log in to your network. It is usually turned off, when you buy the router.
To set up MAC address filtering, you as a WLAN administrator must configure a list of clients that will be allowed to join the network.
First, obtain the MAC addresses of each pc from its operating system or configuration utility.
Then, you enter those addresses into a configuration screen of the wireless access point or router. Finally, switch on the filtering option.
(Not really necessary for home users)