There are many ways when a hacker would try to scam you into receiving a file etc, so that you will take the bait and help him with the trojan/virus installation on your hard disk drive. If you need just one way to stop being hacked, the best way is to install an all-in-one solution with anti-virus, firewall and anti-spyware solution.

We personally use Norton Internet Security and we update our subscription every year. Another similar product which you may consider is ZoneAlarm, but we recommend Norton for their years and track records in the anti-virus arena. btw, we don't get commission for recommending, so you can trust our advise. Not to forget that I am a trained hacker myself.

Nevertheless, you must know that whether or not your PC will be hacked will depend very much on your actions as well. For example, downloading files from warez sites and poor habits of opening up strange email attachments, is as good as inviting hackers to break your door. Some time ago, I have the opportunity to try removing a malignant spyware installed on a friend's machine. It took me 8 hours despite my experience, and eventually we had to reinstall the entire OS. Some of you might say that I should have reinstall it after a short tryout, however, I preferred to take the challenge but failed. :)

Prevention is always better than cure. If you would like to take the risk, a common practice (for some of us) is to use another PC when we need to do something risky. With constant PC upgrades, many of us could easily keep an older PC (at least one) just for this purpose. This reminds me of the hacking class that I attended a few years back - the instructor had to reinstall all the workstations almost every lesson to get rid of the remaining virus or trojans from the previous lessons.

Another way of getting into trouble is to visit cracks, warez, and keygen websites. There are several ways which your PC may be infected:

1) Clicking on buttons on the site which activates malicious scripts.
2) Told that a particular program does not work and requires you to download a another program or extension.
3) Trojans, virus or spyware hidden in the software cracks, or keygen.

Althought we did mention earlier that you must have at least one security software installed on your PC, however, it is impossible to guarantee that the software will definitely protect you against Any or All the possible viruses, trojans and malicious programs.

If you find that your PC behaves abnormally, such as unsolicited pop-up ads, shutting down of applications, poor internet connections (or busy connections), etc, there is a good chance that your PC is infected. You will need to waste quite a bit of time to either remove the infected file, or to reformat and reinstall the entire harddisk again. Again, prevention is always better than cure.