I was quite ignorant about the game at first, but there's a simple mechanism behind your move. If your aim, speed, and strength are all greater than those of your opponent, you're most likely to get a 3 points lead(hence explains the frag with superior speed, strength, aim msg).
And the weapons as already explained.
Remember you can buy double damage, and skaarj targeting sensor from shops, so you can surprise higher exp folks and beat them with these status. It's especially good if you have a high price item like the widowmaker on the prize list.