Be Prepared - it's a song in The Lion King, the motto of the Girl Scouts, a popular safety mantra - and, it's one of the MOST IMPORTANT tenants of stage management!
We all know the benefits of thinking ahead - carefully planning out your routes, expertly packing for any surprise situation, and so on - but oftentimes, time gets in the way. A busy schedule can cause people to forget or forego even the most important necessities (phone, keys, wallet), putting them in a rough spot. That's where you, the awesome stage manager, comes in!
When you're stage managing a show, you'll have your entire kit, so you'll be able to supply most of the room with whatever they need (top requests are usually pencils, band-aids, and Advil).