The best way to PK successfully is by springing surprises on people. I mean, if you have 99 str you can hit like 40, where as with your strength you could probably hit like 20 max, and at at 20 HP the other player is going to eat. A similar rule also applys for if you use a DDS, at your max hit range, they're just going to eat. Stick to your pures or get strength maxed on your main.