These days, Group Discussion (GD) has become an important tool for filtering candidates. The simple rule for candidates can be summarised as -
1. Speak but Speak sense - Remember it is a GD, you need to participate, in other words, Speak up. If you dont, you are out. Keep in Mind to speak in line with the topic of discussion and not something tangent to the topic.
2. Dont Fight - You are no doubt competiting with the rest of group, but dont get into fighting mode. It would create chaos and you would get negative marks. If you want to counter opinion of any other participant, do it politely.
3. Contribute - You may find that someone has pitched in with a really good point. If you can add something to what has already been said, dont hesitate.
4. Be a starter - If you are comfortable with the topic, you may take the lead to start the discussion.
5. Take notes - It is important to take notes during the discussion - You might be asked to summarise at the end of discussions.