1. Have a backup plan in case of weather issues.
For guests sensitive to heat, provide plenty of shade and ice cold drinks. If the weather
is cool, keep blankets nearby in decorative baskets.
If windy or rainy, have a backup venue available--you don't want your party to be remembered for the wrong reasons...
2. Oh, Baby!
Babies or Children coming? Remove potential hazards and do a quick baby-proofing of the environment. Consider providing private areas for feeding or calming a baby. Parents and other guests will appreciate it.