Research the event on the web and get a sense of the attendees. Research the people you want to meet and use that information to break the ice with them.
Wear a comfortable suit and make sure you can reach your cards without fumbling.
Walk The Walk
Walk into the room confidently and smile meeting the eyes of those persons you are interacting with.
Circle the room so you can get an idea of who is there, then focus on a few carefully chosen ones working through your list of priority.
Spot Lone Wolves
If the room is crowded look for people who are standing alone. It is harder to integrate into a group of strangers and individual contact is best. One-to-one makes for the most effective networking since you can focus more giving all your attention to that person.
Make Meaningful Connection
Ask others about themselves so you can connect to their interests and lives. Do not start off with your 30 second commercial about yourself, be genuinely interested in who you are talking with. Be an active listener, listen without interupting, comment or ask questions when it is appropriate. Remember you have to pass the test as a personable human being first before people will want to do business with you.
Ask for a business card instead of offering yours, it is less presumptuous.
Get An Introduction If Possible
An introduction is like an implicit endorsement and the next time you meet that person there will be that association and context.
Give And Take
Always try to be helpful. Help others to make connections and share helpful information. When you help others they want to help you in return.
Remember you might not close a deal but you might get the right to follow-up with a call or meeting which could lead to a very meaningful business relationship. Even one contact like that makes an evening of networking worthwhile.