First of all, you need to have an effective anti virus software installed on your PC. In case you are using Macintosh check for the appropriate version before you download it. The MOST popular anti virus software are Norton's anti virus and MacAfee's 'Virus shield'
1. Update your anti virus programs regularly either by visiting the producer's web site or by turning ON the auto update feature.
2. Turn ON the auto scan in your antivirus. This runs a scan session every time you boot your computer looking for infections and automatically deleting them in the background. Even the best anti virus needs your intervention when the anti virus software can't delete worms by itself.
3. There are some stubborn viruses. For viruses that don't budge, what you need to do is search for more information on the net, websites of anti virus makers contain definitions and removal information of all known viruses. You can use this to get rid of your virus. You can, alternately, search by the name of the virus itself.
4. If you have to download any patches (bits of software for your anti virus) do it. This will almost always remove most of the infections.
5. Certain adwares can't be caught or detected easily, in such instances you can run another anti virus. And follow the instruction carefully.
6. You should know why anti virus programs score over deleting viruses. Viruses corrupt files in addition to creating new files. First of all it is hard to detect all of them apart from the dangers of deleting the necessary files too.
I hope this guide helps you! Please rate my guide helpful if you think this has helped you solved your problems.