Wi-Fi access is a convenient way to save yourself from paying massive overage fees to your mobile provider, but there’s a risk involved when it comes to public Wi-Fi.
Criminals can create malicious access points, or hijack access points that were poorly configured. In fact, creating a fake access point and tricking people into connecting to it is literally child’s play, as a 10 year-old proved this summer during DEF CON.
If you don’t need Wi-Fi while out running errands, then you should avoid connecting to any of the access points listed. If you do need Wi-Fi, then using a VPN (virtual private network), and sticking to websites that use SSL is a way to lower some of the risk, but it won't eleminate it completely.
"[A VPN] will securely transport your traffic through the network you're currently on, into another one. This makes it extremely difficult for coffee shop networks, or attackers targeting your mobile phone to perform what are called man-in-the-middle (MITM) attacks. VPNs are handy to have while traveling abroad, or sitting in coffee shops," Tentler explained.
If you're looking for VPN options, F-Secure has Freedome VPN, and there are services from Buffered VPN and IP Vanish.
Unless you've configured it yourself, each VPN offering will require payment. Remember the golden rule, if you're not paying for the product - you are the product - so avoid free VPN offers if possible.
If you are using public Wi-Fi without a VPN, you should avoid conducting any banking or online shopping, as it’s usually safer to do such things from home.