From some quick testing on EU_1(I am an NA player so this might be inaccurate as I didn't get much hitting in with my Cali ping), it seems as if you get points for the amount of hp damage you do. Don't know how many points per hp, but it seems to be linear-ish. You lose points by hurting yourself, for example fall damage, and the penalty is fairly severe. I lost 3 points for losing about half my health from a fall. I got 1 or 2 points per hit I did to someone. It also appears that you get points for damaging mounted horses. All of this is from maybe 20 mins of testing so don't hold me to any of that.