You buzz your lips like you're making tugboat noises to your favorite (only) baby nephew. Maybe you sing a snippet of something to calm your nerves. The crazy thing? You are totally not the only person singing in a stall in this particular restroom.
To take listeners through those seemingly difficult first steps, here's a playlist of good introductory excerpts for those new to opera. There's something for everyone, and some you're sure to recognize. Have a listen!