1. always be the initiator and concluder of the GD then being a
participant.
 
2. But if you are participant always try to be the most vial/key
participant.
 
3. put points firmly and always try to get others support too.
 
4. if you find that the discussion os going off-track then  never loose
an opportunity to bring it back to stream this is the best point to
score max.
 
5. try to keep latest information on the topic.
 
6. be very polite , people may try to provoke you to to get more points
but try to keep cool.
 
7. most important don't wait for your turn to speak when discussion is
on. interrupt politely if you want to put forward your points.
 
8. last but not the least keep a tab on the time given for discussion.
score points by wrapping up the discussion if you feel that the  discussion is heating but the time is going to be over.
 
9. during conclusion, do end with the conclusion note. that shows your
     leadership quality.
 
Best scoring points are:
 
1. initiation of discussion,
 
2.always keeping/trying to keep discussion on track
 
3. conclusion on time
 
4. your capability to keep your cool and listen as well as putting your points.
 
5: be a leader.
 
GD basically means searching your team player, leadership, communication capability.