Tip 1: Don't install software you don't use.
Most software has vulnerabilities and the more software you have installed the more likely you are to have one of those vulnerabilities exploited. It is hard to know what software you use and don't use sometimes but you can always uninstall it and if you need it you can install it again later.
Commonly installed software that you might want to consider removing:
Java - If you don't use java applications or java applets. If you need it you can always re-install it from the link below.
Apple Quick-time/iTunes - If you don't have an iPod or buy things from the iTunes store. Quicktime player may be required for some web content (but again, you can always re-install if you find that you need it).
Adobe Reader - This is used for viewing PDF content both online and stored on your computer. Most people will want a PDF reader but if you use Google Chrome browser there is a PDF reader built-in. The Adobe Reader supports more features than most other readers so you may want to keep it, be sure to update it regularly.
Tip 2: Use the ad block plugin in Firefox/Chrome.
This removes ads from sites that you browse which are the primary source for most drive-by installs.
Tip 3: Use the latest version of your web-browser.
The latest version of most web-browsers have features that make it harder to exploit vulnerabilities.
Or IE 8 (Windows XP) / 9 (Windows Vista/7) via windows update.
Tip 4: Keep your software up-to-date.
Windows (and Microsoft Office): Go to start -> all programs -> Windows/Microsoft update. Microsoft releases updates on the second Tuesday of every month and occasional security updates at any time.
Adobe Flash Player: http://get.adobe.com/flashplayer/ (version 10.3.181.14 as of 5/18/2011)
Flash player should also request an update when your computer reboots (usually).
Adobe Reader: http://get.adobe.com/reader/ (version 10.0.3 as of 5/18/2011)
Reader will also request updates from the system tray (by the clock) if updates are enabled. This will only upgrade the version installed not upgrade to the latest version (Reader 9 to Reader X).
Java: Go to Control Panel -> Java -> Update -> Check now (version 1.6.0 update 25 as of 5/18/2011)
Java will prompt you to update from the system tray but is set to check only once a month by default and will not download the update automatically. I recommend that you change the update settings to check every day and automatically download the update (from the control panel as above).
You can also download the latest version from: http://www.java.com/en/download/index.jsp
Quicktime/iTunes: Use the apple software updater from your start menu (version 7.6.9 for Quicktime and 10.2.2 for iTunes as of 5/18/2011).
Be sure you don't accidentally install extra software that you don't want (Apple sometimes has extra software checked by default).
You can also download the latest version from: http://www.apple.com/quicktime/download/
I hope this has been helpful for people. I'll try and post whenever there are new releases of software that need updating.
