RE: Body Language.
Move slow, talk slow, be an approval giver (not a seeker). We all have the capacity to be at the level of Bill Clinton or other legendary communicators - we do it on first dates, job interviews - he does it all the time. One of my most networked/outgoing friends consciously goes into certain situations like 'she owns the venue'. Also if you talk to everyone, you can hide the fact that you are interested in not everyone. You might also try videotaping your body language when you are with friends/familiar situation vs strangers/safe situation. You will have to try this to realize the power of this - but if you really, really want to talk to a group or even a cute female who is seated alone/together, drag a chair over from the other side of the room (noisily if possible) and sit down with them. That demonstrates commitment and is an opener all-in-one.
RE: Peer ratings
They are a form of social proof (raters do not exist in a bubble).
"Similarly, a person who has been unemployed for a long time may have a hard time finding a new job - even if they are highly skilled and qualified. Potential employers attribute wrongly the person's lack of employment to the person rather than the situation. This causes the potential employers to search more intensively for flaws or other negative characteristics that are "congruent" with or explain the person's failure and to discount the applicant's virtues."
One of the more clever and disturbing ways to gain 'power' over an individual is to play the student in the master-student role. E.g. by having them teach you something - which is doing you a favor, you can gain their favor.
Ben Franklin: http://news.ycombinator.com/item?id=145544