When waiting at a junction to turn right across traffic, always leave your wheels facing forward. The video below shows why: the driver is waiting to turn and has his wheels turned in the direction of the road he wants to turn into, but a following car runs into the back of him and shunts him into the path of an oncoming lorry. It could have been so much worse, but fortunately the lorry took enough evasive action to make it a glancing blow.
The dual dashcam footage shows how violent the double impact was.