I just had a gig teaching the teens at The Palace Summer Workshop the care and feeding of costumes. Or, actually, the care and non-feeding of costumes.
I showed them how to consolidate each costume onto two hangers, connected by a grocery bag hanging over the both of them, containing hat and shoes. I reminded them not to eat or drink anything while in costume, and to hang it up.
I explained that costumes are not interchangeable...that each was designed for the individual character, and, if they like someone else's better, then they should have auditioned for that role.
I told them that people in other eras wore their clothes differently than we do, today. If you are wearing a hoop skirt, you have to walk differently. A flapper dress is not just a dress, it's a social statement. I told them to research their show, and the time and place in which it was set, and reminded them that Google is their friend.
I told them that their costumes define the setting for the play, as well as the character they are playing. I explained that, if they didn't wear them exactly as directed, they would lose their audience, because those watching would be distracted from the action by anachronisms.
I promised them that, if they needed a repair, somebody would do it for them...all they had to do was to tell the Wardrobe Mistress.
I pointed out that they, as actors, are rewarded by applause from the audience, but techies are rewarded with respect from actors.
I reminded them that we are all Assistant Story-tellers, and no one is more important than anyone else in the production hierarchy. Except the Director. He or she is God, in the Universe of the Play.
I hope I didn't leave anything out.