Before backing up, always check first to make sure the area behind is clear.
If you are backing in a straight line or on an angle to the right, turn your body and head to the right, but check left frequently if there is a possibility anything could be coming from that direction.
If you are backing on an angle to the left, turn your body and head to the left, checking right periodically. Remember, your front end will swing wide as you turn. Ensure there are no objects in its path.
Back slowly and DON'T rely solely on your rear-view mirror.
When a truck driver is backing up he has to use side mirrors. Even though they are very large mirrors, they still leave a big blind spot. So be patient and never cross behind a truck, which is preparing to back up.
Finally, avoid backing into a blind area without a guide.