Operation System

Windows 10 Edition (and higher) and macOS are both secure options. If you have the ability, you can choose Linux, such as Ubuntu, or even extremelysecurity & privacy focused ones like Tails, or Whonix.

On the topic of Operation System, the most straightforward security principle is: pay close attention to system updates, and apply them asap when available. The capability to master the Operating System comes next. People might ask, what on earth do you need to learn in order to master an Operating System like Windows or MacOS? Isn't it just clicking around? Well it's actually far from being enough. For novice users, a good antivirus software, like Kaspersky, BitDefender, is a must, and they both are available on MacOS.

And then, don't forget about download security, which I mentioned before. You will have eliminated most of the risks, if you don't download and install programs recklessly.

Next, think about what you are gonna do, if your computer got lost or stolen. Having a boot password is obviously not good enough. If disk encryption is not turned on, bad actors can just take out the harddisk and retrieve the data inside. Therefore, take the time to enable disk encryption.

https://docs.microsoft.com/en-us/windows/security/encryption-data-protection https://support.apple.com/en-us/HT204837

https://veracrypt.fr/ - Powerful encryption tool (formerly TrueCrypt).