We all are accustomed to using firefox. But, have you been giving any thoughts to browsing safely using firefox. Just keeping it updated will not secure your browsing. To achieve a good degree of pc security, you need to know how to secure your brower. This is not going to be a comprehensive post about firefox, I'm sure a lot would be left unsaid, still, I'll help cover the basics. Using the points described, you'll be able to secure your firefox to a good extent. Let's go... Things to noticeThe default firefox installation. There are few things to tweak right in the default firefox installation. Like, if you have been storing a lot of passwords, it is a good idea to set a master password to prevent other users from accessing your passwords easily. The other users could be your friends, officemates, brother or anyone else you'd not like to disclose your passwords. 
Other things to take note of are history, cookies and saved form information. Firefox by default saves form information and history and cookies also (sadly you can't eat these cookies, they're just for the browser to relish!). If you feel the need, you can delete your browsing tracks, cookies and other information from Tools -> clear recent history. This comes very handy if you're using a friends' computer or accessing internet from outside in an internet cafe etc. Although if you're continuously using internet from a machine other than users, I will strongly suggest you activate the built in 'Private browsing' mode from Tools menu. 
Firefox with addtional addons for security and privacyNow, lets put some addons to increase our pc security and privacy. Prefbar Let's start with Pref bar which comes very handy when you have to change firefox settings on the fly. This is the one I always install with my installation of firefox. With pref bar, you get the power to control and change firefox options on the fly. You can disable or enable popups, cookies, referer, fonts, colors, javascript, java, images, flash and a lot more. Do not miss this. While browsing, just make sure you avoid java, flash unless absolutely necessary. You could also try turning referer unchecked for a little more security. Although, you'd be needing it on some sites. 
NoScript - Next comes noscript which has been around for years and one of the main addons for safer browsing. As the developer says, The best security you can get in a web browser!
It'll allow active content to run only from sites you trust, and protect yourself against XSS and Clickjacking attacks. You can enable and disable script on per site basis with this. That means you can selectively allow which sites can run scripts. The other ones could then be blacklisted.
Adblock plus - Looking to block adds and those nasty popup and popups and all types of flash and stupid image banners that you don't like seeing. Adblock comes to the rescue.
A very handy and effective tool to block advertisements and other online nuisances. Install Adblock Plus now to regain control of the internet and change the way that you view the web. The add-on is supported by over forty filter subscriptions in dozens of languages which automatically configure it for purposes ranging from removing online advertising to blocking all known malware domains. Although it has been found to leave some trail as some sites are found to be identifying that adblock is installed on the browser and request users to switch it off before allowing access. Needless to say, with a very little effort by installing above addons and modifying firefox settings a little, you'll be able to attain a good level of browsing security. And, safer browsing means better pc security.
Other things to take note of are history, cookies and saved form information. Firefox by default saves form information and history and cookies also (sadly you can't eat these cookies, they're just for the browser to relish!). If you feel the need, you can delete your browsing tracks, cookies and other information from Tools -> clear recent history. This comes very handy if you're using a friends' computer or accessing internet from outside in an internet cafe etc. Although if you're continuously using internet from a machine other than users, I will strongly suggest you activate the built in 'Private browsing' mode from Tools menu. Firefox with addtional addons for security and privacyNow, lets put some addons to increase our pc security and privacy. Prefbar Let's start with Pref bar which comes very handy when you have to change firefox settings on the fly. This is the one I always install with my installation of firefox. With pref bar, you get the power to control and change firefox options on the fly. You can disable or enable popups, cookies, referer, fonts, colors, javascript, java, images, flash and a lot more. Do not miss this. While browsing, just make sure you avoid java, flash unless absolutely necessary. You could also try turning referer unchecked for a little more security. Although, you'd be needing it on some sites. 
NoScript - Next comes noscript which has been around for years and one of the main addons for safer browsing. As the developer says, The best security you can get in a web browser!
It'll allow active content to run only from sites you trust, and protect yourself against XSS and Clickjacking attacks. You can enable and disable script on per site basis with this. That means you can selectively allow which sites can run scripts. The other ones could then be blacklisted.
Adblock plus - Looking to block adds and those nasty popup and popups and all types of flash and stupid image banners that you don't like seeing. Adblock comes to the rescue.A very handy and effective tool to block advertisements and other online nuisances. Install Adblock Plus now to regain control of the internet and change the way that you view the web. The add-on is supported by over forty filter subscriptions in dozens of languages which automatically configure it for purposes ranging from removing online advertising to blocking all known malware domains. Although it has been found to leave some trail as some sites are found to be identifying that adblock is installed on the browser and request users to switch it off before allowing access. Needless to say, with a very little effort by installing above addons and modifying firefox settings a little, you'll be able to attain a good level of browsing security. And, safer browsing means better pc security.
Download ccleaner enhancer and install over your already installed Ccleaner and it'll automatically integrate itself to the application expanding its cleaning capabilities manifold. Now, next time you think of removing crap from your pc, you know where to turn to. :)