1. Install an Antivirus and Keep It Updated
We call this type of software antivirus, but fending off actual computer viruses is just one small part of what they do. Ransomware encrypts your files and demands payment to restore them. Trojan horse programs seem like valid programs, but behind the scenes they steal your private information. Bots turn your computer into a soldier in a zombie army, ready to engage in a denial-of-service attack, or spew spam, or whatever the bot herder commands. An effective antivirus protects against these and many other kinds of malware.
In theory, you can set and forget your antivirus protection, letting it hum along in the background, download updates, and so on. In practice, you should look it over every now and then. Most antivirus utilities display a green banner or icon when everything is hunky-dory. If you open the utility and see yellow or red, follow the instructions to get things back on track.
You may be thinking, wait, isn't antivirus built into Windows? Not only is Microsoft Windows Defender Security Center baked into the operating system, it automatically takes over protection when it detects no other antivirus, and just as automatically steps aside when you install third-party protection. The thing is, this built-in antivirus just doesn't compare with the best third-party solutions. Even the best free ones are way better than Windows Defender. Don't rely on it; you can do better.
Whether you've chosen a simple antivirus or a full security suite, you'll need to renew it every year. Your best bet is to enroll in automatic renewal. With some security products, doing so enables a malware-free guarantee. You can always opt out later, if you get the urge to switch to a different product.
One more thing. If your antivirus or security suite doesn't have ransomware protection, consider adding a separate layer of protection. Many ransomware-specific utilities are entirely free, so there's no reason not to try a few of them and select the one that suits you best.
2. Explore the Security Tools You Install
Many excellent apps and settings help protect your devices and your identity, but they're only valuable if you know how to use them properly. To get the maximum protective power from these tools, you must understand their features and settings. For example, your smartphone almost certainly includes an option to find it if lost, and you may have even turned it on. But did you actively try it out, so you'll know how to use it if needed?
Most antivirus tools have the power to fend off Potentially Unwanted Applications (PUAs), troublesome apps that aren't exactly malware but don't do anything beneficial. But not all of them enable PUA detection by default. Check the detection settings and make sure yours configured to block these annoyances. Likewise, your security suite may have components that aren't active until you turn them on. When you install a new security product, flip through all the pages of the main window, and at least take a glance at the settings.