Left Turns
Normally, left turns should be made from the far left lane (as close as is practical to the center line) of the road you are turning from (which again, we'll call Highway A) into a lane of the road which you are turning into (Highway B), that is lawfully available to traffic moving in that direction.
An exception is if the road you are turning from terminates at the intersection, and has at least three (3) marked lanes separating traffic traveling in the same direction. In this case, you are allowed to turn left from the center lane and you should enter a lane legally available to traffic traveling in that direction upon the roadway being entered.
Preview
It is against the law to begin making a left turn before entering the intersection.
In order to safely make a left turn:
Drive next to the center line or into the left turn lane.
Signal about 100 feet before the turn.
Reduce your rate of speed; then look over your left shoulder.
Come to a full stop behind the limit line. Look left, then right, then left again. Only when it is safe, make the turn.
Be careful not turn too soon and "cut the corner" of the lane you are proceeding into.
Safety Tip: When you are waiting to make your left turn, keep your wheels straight until it is safe to turn. If your vehicle's wheels are turned left and another vehicle hits you from the rear, your vehicle may be pushed into oncoming traffic.