Wireless Networking
Securing your wireless network is important to prevent against Data and Network compromise, theft of Internet bandwidth and Denial of Service.
Choosing a strong (and long) password
It stands to reason that using a strong (and long) password is important. This can help to reduce the likelihood of an attacker simply guessing (or cracking) it.
Utilising strong encryption and good wireless protocols
Due to security weaknesses in a number of basic wireless network protocols, it is important to choose an effective protocol with strong encryption. The challenge can be that some devices may not be fully supported, so the process may be an iterative one. Implement -> Test -> Tweak.
Authentication
If your user base / seat count is small (e.g. less than 10) you may like to consider adding username and password authentication to your wireless network such as 802.1X
Whilst this can add (yet another password) complexity to setup, it removes reliance on an attacker guessing / cracking a network key alone.
Monitor your network for unusual activity or signs of abuse
We used to recommend that wireless networks be restricted to only trusted hardware (MAC addresses) however this has often proven to be more trouble than it is worth (and trivial to overcome).
A better approach is to monitor the network for all unusual activity. At its most basic level, this involves logging network activity, however more sophisticated options (such as the use of an authenticated web proxy) can help further secure use of the network.