I am curious about this as I had recently moved and spend a lot of time in spaces that offer free public Wi-Fi. I have been reluctant to use it because of security concerns but I would like to save on my data and make use of it in the future. I just want to know what measures I should take to ensure I am being as safe as possible.
First off, you want to always use a VPN. You will want to find a high-quality one that is not used to sell off your data. One I always recommend to people is Windscribe. The paid version is ideal. Make sure the browser you are using forces the use of HTTPS encryption and security. If this is not an option, you can find a browser extension for it. Also, be sure to turn off your WiFi after leaving your home to ensure you are not getting connected to random WiFi. A lot of hackers will use this to their advantage.
Be mindful of network names. This is something a lot of people overlook. What hackers will do is make networks look legit but will use one character off from the registered network so people connect to it without thinking and they can be hacking from a neighboring building or even several miles away.