Hello. A Russian girl I'm seeing while on vacation in Russia has invited me to her 19th bday party. Its gonna be at her place with like 3-6 of her friends, some girls and some guys. There will be booze involved, and I presume everyone will be drinking. I've been on four dates with this girl but just kissing and heavy kino cuz the logistics are shit honestly (I'm staying with my parents while here and she lives with her mom about 45 min away and neither of us have a car). I'm meeting her during the day and we gonna head to her house together via public transportation since idk anything about the small village she lives in. Also I think her mom will be there too lol.

I'm leaving back to US in a couple of days and she knows that. My question is: How should I be/act at the party? How would I go about sealing the deal before I depart? Any advice/insights? Thanks.