The way this Build works is that you'll use the Black Bow to range down enemies. Based on what enemies you are facing, you'll use regular Arrows for trash enemies, or enemies that you won't get much out of triggering Hemorrhage or Poison on because they'll be dead too quickly. Stock up on these, as you can purchase about 700 of them for 7k Runes or so.

You'll use Serpent Arrows and Bloodbone Arrows (Fletched) to deal with tough enemies and Bosses. Using the Barrage ability of Black Bow will allows you to set these Statuses very easily through rapid attacks, but will also deal decent damage in their own right.

Save the Bloodbone Arrows for Bosses because of the three types they are the only ones that are crafted, making them a bit more difficult to get, though it's not incredibly hard at this stage. Note that making the Fletched version is ideal, because it increases the Range of these Arrows. When arrows lands outside of their range they deal reduced damage, so having better Range keeps your damage higher.