Setting wifi passwords would be a good start, but then you'd still have to address the security flaws in wps[1] and upnp[2][pdf].
[1]: http://code.google.com/p/reaver-wps/ [2]: https://community.rapid7.com/servlet/JiveServlet/download/21...
[1]: http://code.google.com/p/reaver-wps/ [2]: https://community.rapid7.com/servlet/JiveServlet/download/21...