Many aspirants get anxious before taking on Group Discussion as most of them either have been guided to initiate discussion with loud voice or they themselves start shouting in pursuit of gaining share of voice in the group.
In GD, selection panel looks for one of the most important quality of domain knowledge. Hence, you must remain focused on the GD topic which has been given by selection panel. The trick to remain focused on topic requires pre GD preparation & practice. One must update oneself with current affairs and General awareness and for this News papers and magazines are the best source of information.