Wash gourds before drying to be sure they are free of soil and other garden debris. Gourds are often dipped in a weak bleach solution of one (1) part chlorine bleach to ten (10) parts water to sterilize the surface and prevent rotting.
Hang gourds for drying in a warm location with little moisture. After drying, the gourd's exterior can be polished with wax or shellac.
A few gourds will develop interesting fungal patterns on their surface as they dry. The fungal growth doesn't appear to alter the quality of the dried gourd and may actually improve its appearance.