1) Manager is not a head HR. People should never address them as head HR when they are Managers.
2) When you are representing your company - Never look left or right when someone is describing about his/her professional experience.
3) Never sit with your hands folded when you are taking interview - It shows you are wasting other's time too.
4) When you are taking interview, you need to be a good listener. Random question can't be asked to a person who has come for the interview from a big group in comparison to your company. You should prepare first what you need to ask.
5) Do not talk about what you can pay unless and until you are not in position to describe what role / responsibility you have to offer or you can't understand what role / responsibility what person in front of you has performed.