Always use stun shot, on any class except an orc.
Once u stun the player, get behind him, u'll land many more critical hits if u attack from the back.
Also because archers have that skill that increases ur evasion while u move, try to move as much as possible when using ur archer.
Recomended archer for this strategy is SR because of the high speed and good evasion.
Archer PvP Guide
Linear Mode
