Best way is to start making out and gradually make your way up to grabbing her junk at last you start touch'n nd squeezn her the just slowly remove it but if she jerks back or pushes u back DONT keep...
To get a girl to do that you probably have to get to know her better and once you do you might want to talk it over with her. If she is uncomfortable with it don't make her do it.
You get the girl drunk first and then go into a room Alone with them and take off yours first then shell be to drunk to know what's going on and BOOM she takes off her shirt for you