Body language says a lot about you. Your mannerisms indicate your many things including bad habits and undesirable personality traits. So how should you stand or sit to win someone over?
When presenting to an audience keep your feet firmly planted on the ground unless you are walk around the room or across a stage. Keep your movements slow and do not get into a continual pattern of walk as this is distracting.
When sitting it is important to show an open posture with your arms. Sit on the edge of the chair and lean slightly forward. Do not lean too far forward otherwise you will look threatening and don't lean back otherwise you will look defensive.
Don't sit with your legs apart. In some cultures this is insulting and in most cultures you will look like a ‘player’. Men like to sit back in the chair and fold their arms behind their head, this is comfortable for us. Unfortunately it makes us look like an arrogant pig.
Regardless of whether you are sitting or standing, always remain square-on to your audience. Even if the person is a physical threat to you, you should remain facing them. If you turn sideways you will look defensive and if it is an angry person it will look to them like you want to fight.
Always keep your head up and still. This shows an interest and also keeps the carotid artery open so that you can get that much needed blood into your brain. Slow nods of the head are good when talking to an angry person.
Lastly, maintain about 60 to 80% eye contact in general conversations. Any less than that makes you look shifty and any more than that a bit creepy. For angry people use about 30 to 60% of eye contact. To control a conversation, look at the person when you are talking and look away when it is their turn to talk.