Wooden or bamboo skewers should be soaked for at least 20 minutes. They should not be soaked for longer than four hours. The skewers can be soaked in water, but soaking them in wine or juice gives an added depth of flavor to meats.
Bamboo skewers can normally be reused as long as they have not become burnt during their time on the grill. A quick way to get the skewers on the grill faster next time is to wash them, soak them and then freeze them in a bag after they are done being used.
Soaking skewers helps prevent them from becoming burnt or catching on fire while on the grill.