To start a dominance struggle inside of a role play, I simply choose something a girl has said or done (or not said or not done), and I tell her:

Listen, I know we’ve only been dating like 6 months, but if you ever do that again, we’re over!

Done correctly, this should start a back-and-forth verbal jousting for dominance between the two of you.  You’ll know that you’ve won a dominance struggle when the girl backs down, gives up, laughs, or just outright says “Okay, you win.”  When you win a dominance struggle, she’s attracted to you and you should get logistics ASAP!   And since you might now quite know about that yet, conveniently that is what the next tutorial covers, so enjoy!