Call one of the girls to arrange a date, then pick her up within 1 hour (2 real-time minutes) and take her to one of the activities shown on the map.
Note that you cannot date a girl when you are on a mission.
Do not wear anything from the Russian clothes shop.
Her favorite activities are drinking, going to shows (strip clubs included), and darts. Special Ability: Health Boost - Call Carmen to restore some health. Check out the “women seeking men” section under CRAP personals, scroll down and (despite your better judgment) click on the “Party girl seeks man for NSA fun and blog material - 29 (Lancaster)” post. Alex only likes clothes from Perseus and upscale cars (Turismo, Super GT, etc).
Dating multiple girls at once is a risk if one of those girls is Kiki Jenkins, because she starts to stalk you, and eventually dumps you if she catches you with another woman.