Let's start with the basics -- enabling your firewall is the first layer of protection for your PC. Firewalls can stop malware and intruders from compromising your system, and it takes no more than selecting 'On' to implement on both Windows and Mac systems.
In the latest Windows 10 build, go to Search --> type Firewall, and select Turn Windows Firewall on or off. In Mac systems, go to System Preferences --> Security and Privacy, and then make sure the Firewall button is green and enabled.
Virtual private networks (VPNs) are a popular way to disguise your Internet activity, but they can also be a way to protect your communication channels. VPNs, available for free and by subscription, provide a level of encryption which can prevent eavesdropping -- which is particularly important when using public networks.
While VPNs are a good start, using HTTPS, a protocol which encrypts requests sent to a domain, can also help keep your data safe. While usually found on sites which deal with financial transactions, using browser extensions such as HTTPS Everywhere activates encryption on websites which support the protocol. The add-on is available from EFF for the Chrome, Opera and Firefox browsers.
The hotspot is public and you don't know how secure it is, nor are you in control. Therefore, you should avoid accessing any sensitive accounts -- such as financial services or online payment providers -- as a matter of caution. If malware is present and your keystrokes are being recorded -- or a man-in-the-middle attack has been performed -- you will be letting yourself in for heartache later. Wait until you get home.
Double-check for any spoofed hotspots before you connect, as they may look official but lure you to download malicious software. Spoofed hotspots may appear legitimate with names such as "Free Wi-Fi" or duplicating a retail store's hotspot i.e. "Starbucks WiFi." but are actually gateways for attackers to conduct phishing campaigns, MITM attacks and surveillance. If a hacker conducts a man-in-the-middle attack, any communication sent from your system to online services may be spied upon, leading to data theft or potential malware payloads being deployed.
If you connect your device to a public Wi-Fi hotspot and your system is out-of-date, vulnerabilities may exist in your software which are avenues for hackers to infiltrate. Make sure all of your software is bumped up to the latest version to reduce the risk of exploit.
Online service providers are rolling out two-factor authentication more widely as data breaches become more common. By linking accounts to a mobile device and requiring a second layer of authentication before being granted access to an account -- such as inputing a code sent to your smartphone -- even if credentials are stolen via public Wi-Fi networks, attackers still cannot compromise your account.
While connection features offered by smartphone vendors which automatically switch from mobile roaming to open Wi-Fi networks can save you on your bill, they can also put you at risk if you're not careful. For the sake of security over convenience, consider turning these features off so you can control which networks your mobile connects to manually.