1. Create bulletproof passwords
Keeper
2. Keep software up to date
UCheck, Glary Utilities (Software Updater), Secunia PSI, Kaspersky Software Updater. Although as others rightfully mentioned above, CCleaner's case is the proof that sometimes latest isn't necessarily the greatest.
3. Use reputable antivirus software
Bitdefender Total Security, Malwarebytes Premium, Zemana Antilogger, plus several others for on-demand daily scans
4. Email with caution
Always. I don't use free mail services, and I filter everything with SpamDrain.
5. Don’t forget about your mobile device
My Android phone is protected by Bitdefender mobile security and behind VyprVPN. Plus, I periodically run on-demand scans with Malwarebytes, Zemana, and Comodo.
6. Use two-factor authentication
Yes, always (whenever possible).
7. Be wary of public Wi-Fi
I almost never use public Wi-Fi. If for some reason I find myself that I have to, I am always behind a VPN.
8. Browse using an encrypted connection
VyprVPN, AdGuard, HTTPS Everywhere.
9. Use an adblocker
I have been using in different combinations AdGuard, Adblock Plus, Ghostery, etc.
10. Customize privacy settings
I play around a lot with security product settings and configurations in my virtual lab to see what it works for me and what doesn't. I always try to strike that stability and security balance for my systems.