Being around strangers at a party

I recently got invited to a pretty "popular" persons 18th birthday party at this speakeasy, it was a bit out of the blue as we had never really talked but were introduced by a mutual. I am a bit concerned going because I have 2 other friends going but don't have anyone else. I want to be able to reach out and be able to be more comfortable around everyone else instead of just sticking behind my 2 friends, especially since they know other people going to this party. What are some conversation tips or just skills I can have in mind to be able to go up to them? and possibly be more open and approachable myself?