Besides updates and patches, there are several tools to make your Firefox or Flock browser safer.
NoScript, MacAfeeSiteAdvisor, Netcraft Anti-phishing toolbar,
Clear Private Data (standard available Ctr-Shift-Del), Password Maker, DrWeb Anti-Virus link checker are the first to think about.
I would also think about adblock plus + filterset G-updater, and the update notifier.Safe search with: www.scandoo.com
Who knows of any more security add-ons or plug-ins?
How do some of these measure up polonus? Worth a look
CookieSafe 1.0.8
The CookieSafe extension allows you to control which websites have permission to store cookies on your computer.
Distrust 0.5.5
Distrust is a Firefox extension that came to fill the need to privacy on your computer. Distrust aims to create a silent browsing experience which means that the browser should leave the computer as it was when browsing began
INFOCon Monitor 0.3
INFOCon is a Firefox extension that will monitor the current SANS INFOCon level as well as the current headlines and put them in a nifty little icon on your Firefox statusbar.
SpoofStick 1.06
SpoofStick is a simple browser extension that helps users detect spoofed (fake) websites.
I hope spoofstick has improved, I used to use it (a long time ago) but it couldn’t detect a simple URL forwarding method. Where the URL forwards you to another website but keeps that website content inside a frame and the original URL is seen in the Address Bar and not that of the remote/redirected content.
Here is another reason, why I think NoScript is a must to have installed inside FF or Flock.
Consider the failed JavaScript On-Unload Vulnerability, a lot of browsers are vulnerable whenever Javascript is installed.
Read about this here, and come to your own conclusions: