Before one immerses a new utensil, he recites the Beracha, "Baruch Ata…Asher Kideshanu Be’misvotav Ve’sivanu Al Tebilat Keli." If he immerses more than one utensil on one occasion, then he recites "Al Tebilat Kelim," in the plural form, instead of the singular form of "Al Tebilat Keli." Nevertheless, if one mistakenly recited the Beracha in the plural form for a single utensil, or in the singular form for multiple utensils, he has fulfilled his obligation and does not repeat the Beracha.
While reciting the Beracha, one should preferably hold the utensil in his right hand. Furthermore, it is proper to stand while reciting the Beracha, just as one should stand whenever he recites a Beracha over a Misva. Some Rabbis found an allusion for this Halacha in the verse (Tehilim 33:11), "Asat Hashem Le’olam Ta’amod" (literally, "the counsel of God shall always endure"). The letters of the words "Asat" and "Le’olam" are "Ayin," "Sadi," "Tav," "Lamed," "Ayin," "Lamed" and "Mem," which represent the words, "Erub," "Sisit," "Tefilin," "Lulab," "Omer," "Lebana" and "Mila." This verse thus alludes to the fact that when one recites the Beracha over these Misvot, "Ta’amod" – he must stand. This applies to Tebilat Kelim (immersing utensils), as well. Nevertheless, if a person sat while reciting the Beracha before immersing a utensil, he has fulfilled his obligation and does not repeat the Beracha. Tebilat Kelim differs from other Misvot in that it is not an outright obligation; one is not required to immerse a new utensil unless he wishes to use it. As such, there is greater room for leniency, and thus one who mistakenly sat while reciting the Beracha does not repeat the Beracha.
One must not speak after reciting the Beracha until he finishes immersing all the utensils he intends to immerse. One may speak in matters related to the immersion, such as asking somebody to bring him another utensil or the scraper to remove stickers. If one spoke in matters unrelated to the immersion after he recited the Beracha and before he began immersing the utensils, he must repeat the Beracha.
While immersing a utensil, one should hold it with a loose grip, in order to allow the water in the Mikveh to come in contact with the entire surface of the utensil. Alternatively, one may wet his hands before immersing the utensil, in which case he is allowed to hold the utensil with an average grip during the immersion. Since his hands are already wet, the part of the utensil that he holds will come in contact with Mikveh water by touching his hands. One may even wet his hands with water from a sink for this purpose, as this water will obtain the status of Mikveh water once it enters the Mikveh (due to a Halachic concept known as "Hashaka").
Many people use baskets with holes in the bottom and sides when immersing several utensils at once. They lower the basket into the Mikveh, and the water in the Mikveh enters the basket through the holes and touches the utensils. This is certainly permissible, but on condition that one places the utensils alongside one another, as opposed to on top of one another. When utensils rest on top of one another, the weight of the top utensil might prevent the water from touching the upper surface of the lower utensil. One must therefore ensure that the utensils are lined across, next to one another, without any utensil on top of another.
Summary: Before immersing a utensil, one recites the Beracha of "Al Tebilat Keli" (or "Al Tebilat Kelim" for multiple utensils), preferably while standing and while holding the utensil in his right hand. He should not speak in matters unrelated to the immersion until he finishes immersing all the utensils. One should hold the utensil with a loose grip, or wet his hands prior to the immersion and then hold the utensil with an average grip. Perforated baskets may be used to immerse several utensils together, provided that no utensil is placed on top of another.