Don’t let a cuppa joe spoil your shoot.
If there’s going to be any sort of mess on set at all, such as effects or rain or anything, bring an extra set of clothes. Even if there isn’t going to be anything tricky, having an extra set of clothes handy won’t kill you.
Clothes are small, but invaluable if needed. Like bullets during a zombie apocalypse.
Note, by “clothes”, I also mean “costumes.” Budget for that.