Drying the feet:[1] Placing (socks[2] or) shoes on one’s feet which are wet from bathing can lead to blindness r“l. [Therefore one must dry his feet prior to putting on his socks or shoes as is the law regarding all matters which endanger a person.[3] Nevertheless the custom of the world, including Rabbis and other G-d fearing Jews[4], is not to be particular to dry the feet prior to wearing socks or shoes, and G-d nevertheless protects them from danger.[5] Thus being that this is the custom, and G-d prevents the danger from occurring, one may even do so initially.[6]]
[1] Admur Choshen Mishpat Hilchos Shmiras Haguf Vihanefesh Halacha 9 based on Gemara Pesachim 111b
[2] Parentheses in original. This teaches us that even socks may not be placed on wet feet.
Other Opinions: There are opinions [Likkutei Mahrich Seder Hanhagos Erev Shabbos] which hold that there is no need to dry the feet prior to placing socks. Furthermore if one places on socks then he may even place his shoes on with his covered wet feet. Nevertheless from Admur ibid which adds socks in parentheses it is understood that the hazard applies even with socks. [Shaareiy Halacha Uminhag 3:13]
[3] Ketzos Hashulchan 2:10
[4] Shaareiy Halacha Uminhag 3:13
[5] Machatzis Hashekel 260; brought in Ketzos Hashulchan 73 footnote 1
[6] Based on Teshuvah of Tzemach Tzedek, elaborated on in Shaareiy Halacha Uminhag 3:13.