Then try to roleplay as a psychopathic/sociopathic person. No playing as a good or even a grey character. Play as a truly evil person. Kill people to just cause havoic or for fun....not just for money. But be smart about it....you don't have magical powers to help you....and you can't take many people by yourself....so use your intelligence, like in real life, is a killers best weapon.
Be sneaky.
If you help people in quests...don't do it out of the goodness of your heart....do it because you could get equipment or money...to help you buy better weapons or armor to kill more people. Perhaps even kill the person who gives you the reward.
And your killings won't just be directed towards good people...but evil ones as well. Just because your a monster...doesn't mean you have to work alongside evil.
If you want to know how evil you shoud be this is a good page to look at.
http://tvtropes.org/pmwiki/pmwiki.php/Main/CompleteMonster
This would be a really hard role to play, not only because it would be hard to do in the game world...and still survive, but its also completly opposite of how we gamers act in real life. And i myself have always had an issue in doing evil in a video game....because its sort of against my character. But that doesn't mean others can't give it a try in a video game.

