Upon making a new character, only level up once to Level 2 and make sure that you have a full bar for a fateshift. Then, make your way to the Plains of Erathell, by heading EAST. You'll know that you're there when the whole landscape changes. Just look for a fight and the enemies should be at least 4 levels above you having their names in red.
I got this using a tip on TrueAcheivements.com - in the very first town you come across (I forget the name), go to the jail and pick the lock to get inside (should be an easy lock to pick). Once inside, take the first right and follow the cave until you find the level to unlock the cells. Now crouch down and press up on the d-pad so you can attack unarmed civilians, and then throw the lever. a prisoner will run out and you attack him until he's dead.
The only thing you need to worry about is getting caught by the guards while you kill the prisoner, unless you are trying to get the achievements for being caught committing crimes an the like.
If you are lvl 2 you can just go into the prison (pick the lock, no crime) and kill 1 of the guards, I did that with out reckoning mode on. It's not hard if you play on casual, just have 4 or 5 health potions (or reconing mode ;P)
The only thing you need to worry about is getting caught by the guards while you kill the prisoner, unless you are trying to get the achievements for being caught committing crimes an the like.