When making a left turn at an intersection with no traffic light and no stop sign:

When making a left turn at an intersection, you must yield to oncoming traffic. This is true at uncontrolled intersections, intersections with green lights (when no left-turn arrow is present), and even when you have arrived at the intersection first if you are turning left while another vehicle is going straight. Left turns are one of the most common situations for collisions because the turning driver crosses the path of oncoming traffic; mistakes about gaps, speed of oncoming traffic, or visibility are common. Wait for a gap large enough that you can complete the turn without forcing oncoming traffic to slow down. When in doubt, wait. A clear gap is always available eventually; a rushed turn that causes a crash is not recoverable.