Things I've learned working as a waitress:
1. People do not use gloves as often as they should
I've worked in two different restaurants where chefs DID NOT use gloves when touching food.
2. Sick days do not exist
Once when I was on shift, a waitress threw up in the bathroom from how sick she was and then went right back to work.
3. Holidays do not exist
I worked at a place that was open 24 hours, 365 days a year. Yes, I worked Christmas.
4. Minimum wage isn't that bad
I've worked shifts where the place was dead and I made less than minimum wage per hour at end of the day for the 11 hours I was there.
5. TIP YOUR WAITER/WAITRESS
Short of the person spitting in your food or out right disrespecting you, there is no reason not to tip. People live off their tips. They get paid $2 an hour, if that, and still have to pay out busboys after their shifts.
6. How long a minute is
Working at a diner has made me realize how long a minute is. Minutes felt like hours and hours felt like years during 11 hour shifts.
7. The customer is NOT always right
I know that it's a key principal in the hospitality industry but the customer is not always right. When you order the wrong thing, it's not the waitresses' fault that they brought you exactly what you asked for.
I'm sure there are countless things I've learned in working as a waitress but these seem like the most important.