The tallit gadol and tallit katan, in either case say the berakhah standing. And the custom of Rabeinu the Arizal is that he also wrap his head first with the tallit katan, and afterwards let it down on his body, and therefore he would say a berakhah of "lehitatef" for the tallit katan. And whoever does this, it is good, however whoever does not wrap his head but immediately lets it down over his body and dons it, should say the berakhah al mitzvat tzitzi" and not say "lehit`atef.