house parties are great mate and actually pretty easy to game.
the most inportant thing you can do is as soon as you get there mingle for 30 mins. walk up to every one and say , this is usually easy as like you said there mainly friends already so its easy for them to introduce you to the HB.
secondly from then on make it clear to everyone that your having a good time and then you need to attempt to isolate the HB.
a simple " come come keep me company whilst i get a drink ".
thirdly its important to neg the target and escalate kino , even if its as simple as a handshake - neg , she slaps you - hand on lower back - dance/ hug ( maintain eye contact ).
for kino escalation check out vindicarlos escaltion ladder
http://www.vindicarlo.com/DiCarlo%20Esc ... lo.com.pdf
hope this has helped and let me know how it goes