Better to avoid pinches. Ask your on-site consultant, mom, maid of honor, favorite aunt, or mistress of ceremonies to bring a handful of safety pins to the ceremony and reception. Know the fabric of your gown. Your consultant at the bridal shop should be able to advise you on fiber content and what to do in case of a spill. When you spill something on artificial fiber, it is much easier to get rid of the stain than if you spill something on a natural fiber such as silk.
Natural fibers are hollow and absorb the spill.
In either case, unless the spill is major and makes you uncomfortable, better leave the spot alone until you can get professional treatment for your gown. If you must do something and the stain is coffee, mud, blood, tea or some other water-soluble stain, dab the spot gently with cool water and air dry. Club soda will also work. Grease, lipstick, and other cosmetics can only be dissolved by solvents such as cigarette-lighter fluid. If the solvent contains alcohol, it can also dissolve any dye that may have been used to color the gown.