Before the search, one should recite the blessing "... who has sanctified us and commanded us to destroy chametz," since the search is a necessary factor for the destruction the next day. Even though this is an annual mitzvah, we don't recite the Shehechiyanu blessing. However, some recent rabbis have advised that if one has a new item of clothing or a new fruit [that one hasn't eaten for over a year], one then recites the Shehechiyanu blessing, and has in mind to include this mitzvah as well. If one forgot to recite the blessing ("...to destroy chametz"), it can be said at any point while the search is taking place. If other members of the household are taking part in the search, one person says the blessing and everyone intends to be included by it. One should not speak between the recitation of the blessing and the beginning of the search, unless it pertains to relevant matters. If one did speak, they should repeat the blessing, and ideally one should not speak about irrelevant matters until the search is concluded. Before beginning, one should hide away any chametz that is left for eating the next morning, and cover it with a vessel.