I was interviewed on the BBC last week and asked about body language at parties.
Here are some tips.
1. Stand near the food, thats where people hang out. I suggest that to meet guys stand near the buffaloe wings and meatballs and to meet women stand near the chocolate desserts.
2. Stand were there will be a flow of people so you can keep meeting new people and extracate yourself from someone you wish to stop talking with. If you stand near the entrance so you can greet people as they come in works well.
3. You know the arm cross thing? Use to make you feel secure if you are nervous entering a party, but stop hugging yourself once you plant yourself somewere. Instead hold a drink or plate as a security blanket.
4. Listening makes you much more interesting than talking. Have several provactive questions ready to ask people. Such as, "What's the best thing that has happened to you in the last year?" and who is the most interesting person you have every met? What's the most surprising thing your have heard or read about recently?
5. Make sure your heart is aimed towards the person you are talking to and not toward the exit.
6. Don't sit down unless you are talking with someone and the conversation is VERY interesting. Sitting lowers your energy level, makes you less likely to be approached and can take away the vocal variation in your voice. Lean on a wall or rest your arms on the bar if you have to, but stand up.