Puller: The most common job for an archer in a dungeon party is puller. This is primarily because the bow has the longest range of any weapon. In theory, this means that archers can pull mobs over to the party without intruding on the hostility area of other mobs. In actual practice, many mobs are linked together.
However, it does mean that an archer doesn't have to run as much to trigger a mob's attention. For better information on pulling, see this post or scroll down to where we have quoted it in its entirety. An archer should be able to pull a mob to the party without taking any damage.
Generally speaking, when pulling, you should be using basic attacks so that the tank finds it easy to get the mobs attention focused on him/her. Ideally, you will want to cause a constant stream of mobs to come to the party so as to minimize party downtime.
Balanced against this is the chance of over-pulling. The general rule of thumb, that needs to be modified depending on the circumstances, is to pull the next mob when there is a single mob left and it has about 1/2 to full life. The circumstances that modify this are the ability of the healer to keep the party alive and speed the party kills a given mob.