Being romantic is important too but they also want somebody who like to kinky and sometimes dirty talking.
First, say good things about her eyes, hair, hands,etc but little by little try to speak and emphasize how sexy and beautiful her body is. Girls like that. Don't exagerate! Tell her that you have a really nice butt, try tomguess her bra size and majes jokes about it. Like they look bigger and firm, girls like to receive this kind of things because not everybody tells them that. Be spontaneous!