I will give you a tip, pretend you have no sexual feelings towards the opposite sex EVEN if they are the hotest people on the planet.
Think of them as a little pet. Then you won't be intimidated. Disconnect your feelings of attraction until you establish in your mind that it is safe to flirt with that person and he/she returns the favour. If you don't you will get shy, say the wrong thing and come out with some awful body gesticulation you never knew you were capable of doing and stuff up your chances.
Just be cool and think about what the other person is saying not how her boobs look and how she would look in the kitchen only in her apron doing the dishes, legs spread apart like an eagle.