Stress
The job is no picnic—even when the gig is literally catering a picnic. Most days may be smooth sailing, but a storm is always brewing just on the horizon. It's a job of little panics, like running out of Diet Coke or meat being served to a vegetarian.
The stress level multiplies when you have multiple events going on. If you're popular enough, you may have a wedding, a bar mitzvah, two birthdays, and a quinceañera—all in the same eight-hour period. So here's another free tip: don't overbook yourself. Money may be contingent on the amount of events, but you're only human. One great party is a lot better than three terrible ones.
In the world of hospitality, the moderately high stress level will always be present. The more responsibility you have towards a party—whether running errands, running the floor, or running the company hosting it—the greater your amount of stress.
On the bright side, there will usually be plenty of chocolate at the end of events. Have at it.