Go straight to bar and get a drink. Try to start conversation with someone in the bar line (this can potentially be your first networking opportunity). You an say something about the event "what a great event. have you been to this before?" or "hi my name is X and i'm with X. what brings you here?"
If no one in bar line, then approach groups of 3+ and say "Hi, my name is X, mind if I join you guys?".
Avoid approaching a duo as they could be having a private conversation.
Before you walk in tell yourself that this is going to be an amazing event and you are going to meet X number of awesome people. A couple of deeper contacts are better than 10 small talk contacts.