I agree with each member's valuable gift of wisdom.
- UAC. Set it to at least to default ("Always Notify" wouldn't hurt.) Do not allow UAC to become Un-used Annoying Control.
- Back up your system. Everyone (including myself) needs to do this. So, prepare in the event saving your system might depend on it.
- Do not run downloads when you are even a little uncertain of the source, or when you are unfamiliar with what it is. If you <click> on many links & open many e-mails, consider Sandboxie Free www.sandboxie.com
- Most importantly, use your most effective security extension you already possess as the User in User Activated Control, and patiently allow for your own better judgment.
- Extensions for Firefox are found under tools > Get add-ons.
You might try Addblocker Plus, Ghostery, HTTPS Everywhere, & LastPass which securely manages passwords (it makes life easier + safer!) by memorizing a single master password.
Thanks for sharing your configuration!