First like I usually tell dome of my clients start by scanning the room and know the kind or class of people there then try as much as to listen to what people are saying at the conference people love when others are listening to them then you ask them questions related to what they are talking about then you also know to show you are listening to then and also maintain eye contact to allow them know you are listening to them and you can also make a slight hmm sound to allow them know you are enjoying what they are saying and also smile and be cheerfully .