Ask open ended questions! Don't ask, "did you like the movie?"(or whatever you did)-----all your giving her to respond with is "yes" or "no", then she has to make the effort of extrapolating on what she thought--and a lot of people have a hard time doing that, especially since you didn't ask them to extrapolate.
DO ask, "what did you think of the movie?"---she will then be forced to describe in some detail what she thought of it. She can't just say yes or no.
Ok, so pretend she just says, "I liked it" and stops. Fine. Now ask her "what did you like about it?"
The movie is one example, this can be applied to anything. Just remember to ask open ended questions. Begin them with such openers as "what do you think about....." or "what do you like/dislike about.....", "how does that make you feel?"--this one is important, becasue girls are all about feelings. Let me tell you, this simple trick is great. It lets the other person do all the talking and you have plenty of time to think of another question while they are doing it. It also lets them know you care about their opinion.