You can't do a whole lot about security on a public network since security settings are all in the wireless router.
Avoid sending secure information such as credit card numbers, social security numbers, et. al. over a public wireless network.
For your personal router, I recommend the following:
-Enable 128-bit encryption and do a manual hex code for your key.
-Change the default wireless network name (often called a SSID). When that's done, set the router not to broadcast the SSID.
-If you feel up to it, turn off the DHCP router and manually assign IP addresses. If you do that, use something besides the default IP address range. You can use anything from 192.168.0.x through 192.168.255.x and 10.0.0.x through 10.0.255.x.