Once your operating system is up-to-date, you should also update any other software that interacts with the Internet or Internet content. This includes:
- Your web browser(s)
- Your email client
- Web browser plugins such as Flash and Acrobat
Your web browser and email client may be part of your operating system, and get updates along with it. If your browser is Chrome, it includes its own version of Flash, and “sandboxes” it to reduce (but not eliminate) the risk that a vulnerability will provide access to your machine.
As with the operating system, I’m not going to provide detailed steps for updating every program out there. Search for “update Firefox”, “update Flash plugin” and so on, and find those instructions.
The biggest risk, and the one that you should prioritise, is the FLash plugin for your web browser, which has historically had a lot of vulnerabilities. This is of course not an issue if you’re on iOS, where Flash is not available.