This is an incomplete list of the things that can cause the arrow to hit left for a RH shooter:
1. Eye to the left of the arrow. If your arrow seems to fly toward the target from the right to the left, rather than straight at the target, move your arrow or eye so your eye is over the arrow.
2. Shooting with a straight bow arm. It helps some people to avoid left shots if their bow arm is slightly bent.
3. Torqueing the bowstring, by putting counterclockwise torque on the string with your string fingers. This is caused by not relaxing your string hand. Your knuckles stick out rather than lie flat "cupping."
4. Torqueing the bow, by putting torque on the riser with your bow hand. This is caused by not relaxing your bow hand. If you relax your string hand and bow hand at full draw and your bow wants to change position, usually to a more upright position, you are either torqueing the bow or bowstring.
5. Pulling the string away from your face on release. You should release the string with a straight back pull. This is caused by too much tension in the string arm. You should be holding the bowsting at full draw by using your back muscles, not your arm muscles. Back tension is a whole 'nuther subject. Sometimes this problem is caused by not coming to full draw, in which case your drawing forearm is not in line with the arrow (viewed from above), but is angled to the side.
6. Failing to keep pushing with your bow arm toward the target. When you fail to push with your bow arm toward the target, your shot begins to collapse, and generally your string hand begins to creep forward at the same time. When you release the arrow, your bow hand should either remain in place or move forward slightly, and your string hand should recoil backward toward your neck, not out to the side. Without trying to force anything, try to keep your string hand and bow hand in position after each shot (followthrough) and notice where they end up.
7. Losing focus on your spot. You may think you are focusing on the spot you want to hit, but your mind plays tricks on you and you could be focusing on the arrow tip, or some point in space, and not realize it.
8. Shooting with an arrow that is not properly spined for you bow. Learn to bare shaft tune and shoot with well-tuned arrows.
9. If you are already shooting well, you can move your point of impact to the right by using a softer strike-plate, such as a Martin Rug Rest rather than Velcro or Leather.