If you were turning left at an intersection and you had the right of way and a driver hits you head on who's at fault?

Your words 'right of way' are generally the determining factor. The most common exception is the what is called 'the right of last clear chance'. If you saw the other car and had reason to think he would not or could not stop and you pulled in front of him then it can be considered your fault even though you had the right of way.