Leading a group is not as easy as it sometimes looks. After doing your preparation you should be aware of the lessons being put across in the study. Try to keep the group discussion focused on the main points. You will be amazed at how easy it is for the group to drift off course and start discussing things totally unrelated to the topic in question. There is no point in having an in depth theological debate on the merits and demerits of Esau's actions without relating it to ourselves.
Some people have a tendency to do more talking than others do.
There is no harm in this as long as other people are not denied the chance of talking because of them. However make sure the person or people doing the most talking are not going off point. When leading a group pay attention to body language. Some people just speak out. Others either raise their hands in an attempt to speak or just look at you seeking attention to speak.