I've never done it -- but from what I understand it's about 8 minutes to make an impression.
Dress nicely, but also dress comfortably. Your discomfort will show thru to a person.
Brush teeth, use mouth wash, but not overpowering... Minty fresh is good, medicine breath is bad.
Don't use too much cologne if you wear it.
Don't be nervous, think of this as a fun event, if you meet someone, great...
Not all the women there will be beauty queens, don't show your look of disappointment if she looks like Cruella de Ville, she paid her money just like you and deserves some respect. Be polite.
Introduce yourself with a genuine smile and a firm (but not overpowering handshake)
Make eyecontact - looking at boobies is bad form
at least in the first few minutes, there's a woman attached to those booobies, show her some attention.