1. It might seem super obvious but you can't make a solid connection with someone unless you look them in the eye. When you're nervous you tend to look down or across the room--don't. Try you best to meet his gaze, and hold it.
2. Giggling like a school girl or guffawing are big no-no's but an open, natural laugh shows you have a sense of humour--a trait most guys gravitate towards.
3. Your body language is super important, too. Don't just stand around with your arms crossed--this signals 'unapproachable'. Relax, and get yourself a drink.
4. Don't get all excited and talk about yourself. Take an interest in what the other person has to say. It shows your willingness to accomodate others.
5. Stage a disappearing act and leave once you've chatted for a while and exchanged details. Give him a chance to pine for you--anticipation is exciting!