How to Prevent Joomla from being hacked or exploited

Along these growing years in the development of Joomla,Joomla has came over to be the best and most reliable Content management System. But in recent news coverage we have seen that things can be exploited if you don't take the right precautions ,Joomla sites can be easily hacked by some little tweaks also.
So how to prevent yourself from being hacked??

• While installing Joomla, make sure you chmod all the important files and folders to 644 or so, many people leave it as 777 and so it’s easy for the hackers to get into it easily.
• Always check Joomla security sub forum at http://forum.joomla.org
• Always change the password of the admin once in a week or month; it’s a real tough job for someone who has knowledge in database tweaking to constantly look for changed passwords.
• Joomla doesn’t save your passwords in normal characters, but it saves it in md5 format, so here is the trick. You would find it nearly impossible to calculate the md5 value of your desired password.
• Use a SEF component to hide the default Joomla URL’s , hackers normal search for set values that they know are vulnerable , changing these values with a SEF Component will help stop this, We recommend Artio SEF or SH404SEF to do this.
• This maybe seem stupidly obvious but KEEP YOUR JOOMLA UPTO DATE!....so many people either forget to upgrade or “think” that their release is stable, patches and upgrades are done for a reason, because someone found a security issue or something similar in an existing version.
• Clean up and files that are no longer being used on your website, when getting your Joomla install right, we’ve all done it and installed loads of mods which we either installed and uninstalled or ones that we just done need, get rid of them they could be hiding an known exploit that.
• Change your .htaccess file to cope with the already known exploits paste the following :

########## Begin - Rewrite rules to block out some common exploits
#
# Block out any script trying to set a mosConfig value through the URL
RewriteCond %{QUERY_STRING} mosConfig_[a-zA-Z_]{1,21}(=|%3D) [OR]
# Block out any script trying to base64_encode crap to send via URL
RewriteCond %{QUERY_STRING} base64_encode.*(.*) [OR]
# Block out any script that includes a < script> tag in URL
RewriteCond %{QUERY_STRING} (<|%3C).*script.*(>|%3E) [NC,OR]
# Block out any script trying to set a PHP GLOBALS variable via URL
RewriteCond %{QUERY_STRING} GLOBALS(=|[|%[0-9A-Z]{0,2}) [OR]
# Block out any script trying to modify a _REQUEST variable via URL
RewriteCond %{QUERY_STRING} _REQUEST(=|[|%[0-9A-Z]{0,2}) [OR]
# Block out any script that tries to set CONFIG_EXT (com_extcal2 issue)
RewriteCond %{QUERY_STRING} CONFIG_EXT([|%20|%5B).*= [NC,OR]
# Block out any script that tries to set sbp or sb_authorname via URL (simpleboard)
RewriteCond %{QUERY_STRING} sbp(=|%20|%3D) [OR]
RewriteCond %{QUERY_STRING} sb_authorname(=|%20|%3D)
# Send all blocked request to homepage with 403 Forbidden error!
RewriteRule ^(.*)$ index.php [F,L]
#
########## End - Rewrite rules to block out some common exploits